The practices of digital modeling, simulation, and close virtual viewing are becoming more accessible to architectural historians as a result of the significant advancement of technologies for three-dimensional (3D) digital modeling and virtual environment creation. Long-established, large-scale collaborative projects such as Digital Karnak, Rome Reborn, Virtual Harlem, and Visualizing Venice have demonstrated the potential of such methods for the analysis and presentation of destroyed, damaged, and fundamentally altered historically significant objects and spaces.1 The creation of such research environments requires significant resources, including specialized expertise, equipment, and time. However, a number of platforms and tools have emerged as compelling options for scholars seeking to engage 3D modeling as part of their teaching and research without needing major institutional or external grant-funded support. Two such platforms are SketchUp and Sketchfab.2 While both are proprietary, each offers a free tier that can be used in many contexts. These free tiers are available via up-to-date web browsers; scholars do not need to install any software or purchase particular devices. And the relatively simple graphic interfaces of the free tiers make it possible for scholars to learn quickly while still creating complex visual arguments. This review will take a close look at these technologies and how their building and viewing features can be used for historical analysis and teaching.Through both the creation and the viewing of 3D models, scholars can analyze objects and spaces that no longer exist, that have been damaged, or that are in remote or dangerous locations. These digital objects are facsimiles of their physical counterparts that provide affordable and safe options for scholars and students who are unable to travel to particular sites and support study before and after site visits.Sketchfab provides one way for students and scholars to engage in viewing and sharing models. Once a model has been completed, it can be uploaded into Sketchfab, where viewers can interact with it. The model’s creators can add lighting and environmental effects; presets for how viewers can explore the model using rotate, pan, and other movement functions; and annotations, essentially small pop-up windows attached to particular parts of the model that can contain text, images, and hyperlinks. Models that have been constructed to move can also be animated, and soundscapes can be added to increase the immersive experience. Viewers can choose to interact with models via laptops, mobile devices, or virtual-reality headsets.Launched in 2012, the Sketchfab platform has already been used to provide access to architectural models of structures and spaces of cultural significance that have suffered irrevocable damage or destruction as a result of warfare or natural disasters. A well-publicized example of such destruction took place in 2015, when the Islamic State demolished historic sites at Palmyra in present-day Syria.3 Multiple cultural heritage organizations have since created digital models that offer a form of preservation for current study and possible future reconstruction. Models of the Monumental Arch at Palmyra (ca. 193–211 CE) prior to its demolition, for example, offer viewers a chance to experience the site without the need to travel while also providing 3D records of the arch’s construction and architectural features.4Two organizations invested in 3D digital preservation have approached their reconstructions of the arch at Palmyra in different ways. The Arc/k Project, a nonprofit organization registered in the United States, with the mission to digitally preserve threatened cultural sites around the world through collaborations with local organizations, used existing images crowdsourced from visitors to the site prior to the outbreak of the civil war in Syria.5 Another organization conducting similar work is Iconem, a start-up company based in Paris that digitally captures, re-creates, and collects cultural heritage sites. Iconem created a 3D model of the Monumental Arch’s remains after the 2015 destruction and reconstructed the section of the arch that had been destroyed using transparency to highlight the damage inflicted by the Islamic State.6 Both models, shared via Sketchfab, include annotations that provide context around the site, its destruction, and the methods used to create the models. These models, with their variant goals in visualization, demonstrate the respective organizations’ decision-making processes, from the choices of evidence used (crowdsourced images versus images of the damaged site taken in situ) to the ways in which the models were constructed (entirely photogrammetrically versus a combination of photogrammetry and scanning with computer simulation).7Sketchfab’s scene-building and annotation tools, including those that support different background contexts and transparency, present both models for viewers to explore on-screen and via headset. While the portions of the models created using image or scan data are rendered at a relatively low resolution (zoom in to inspect a column capital closely, and one sees that its details have been flattened by the modeling process), Sketchfab’s renderers do give enough of a sense of the architecture’s structure and decorative elements that the models can supplement text, images, and other media as resources for study.8Initially described as the “YouTube of 3D models,” Sketchfab is a web platform for viewing, interacting with, and sharing 3D models and animations.9 In 2021, it was purchased by Epic Games, makers of the award-winning game Fortnite and the virtual environment builder Unreal Engine.10 Initially, the site provided a simple online viewer for zooming, panning, and orbiting 3D scenes and objects, but the platform’s developers have since made significant additions to its functionality. Features now include a variety of customizations for scene building, the ability to annotate specific parts of a model or scene, viewer compatibility for virtual- and augmented-reality contexts, spatial sound and movement, collaborative editing, and the abilities to download, export, and embed models. The platform has a broad and diverse audience that includes game developers and artists, advertising agencies and retailers, cultural heritage scholars and institutions, and adult entertainers. Models of cultural heritage sites such as those of the Monumental Arch are not uncommon on Sketchfab. Museums and other cultural heritage institutions with the resources to scan and photograph their collections now make 3D models of their holdings, and of their galleries, readily available on the platform.11If Sketchfab is one important tool for close viewing, SketchUp can be a key tool for those new to modeling as well as those seeking a simple modeling interface. One of many 3D modeling software packages available, SketchUp was designed and launched in 2000 by @Last Software, a company based in Boulder, Colorado, as a “more intuitive and accessible 3D modeling tool” for architects, engineers, and construction professionals. Its innovation at the time was to offer a simplified interface, meaning an interface with fewer menus, icons, and multistep commands, in which a creator “simply draws the edges of the desired model in 3D space and the software automatically ‘fills’ the shapes to create 3D geometry.”12 This was an important selling point, considering the complexity of other modeling platforms, which often feature many menus and require multiple key strokes and/or mouse clicks (which can take a considerable time to learn) to complete a single command.SketchUp’s designers also made it an early adopter of compatibility, interoperability, and extensibility principles: the software is available for both PC and Mac, it reads and exports files in formats legible to a variety of other 3D software programs, and community members can build small programs—extensions—that expand SketchUp’s core functionality to meet specific needs. This last feature resulted in Google’s 2006 purchase of @Last following the company’s development of a Google Earth plug-in for SketchUp. After continuing to develop SketchUp through 2012, Google sold the software package to Trimble, a mapping and surveying software company, which has since implemented a web-based version of SketchUp. The shift to an online modeling platform means that students and instructors no longer need to download and install software on their personal or institutional computers—processes that can present a range of challenges. Instead, a user needs only a computer with an Internet connection and a browser that supports the SketchUp Free platform. The paid version, SketchUp Pro, which provides a number of advanced features, is available for educators and students at $55 per year or by volume for lab licensing at $30 per seat per year.13 Even with its simplified interface, SketchUp offers a space for building complex historical models that are useful not only for research but also for teaching.In addition to examining buildings directly, architectural historians rely on close visual analysis of historical documents, plans, drawings, and paintings to develop their scholarly arguments. For some scholars, such “close looking” includes sketching their objects of study as a way to focus their attention on minute details of shape, style, and proportion and to identify further questions as they work.14 Art historian Ellen Hoobler and her student collaborators have argued that 3D modeling performs a similar function: “It forces sustained close looking and a quality of focused attention to representing a given object or space.” Using 3D modeling to gain a better understanding of Zapotec tombs at Monte Albán in Oaxaca, Mexico, the research team found that the modeling process “obligate[s] you to be much more concrete than sketches are in representing your understanding of the physical context of objects and buildings.”15 This need for greater precision meant that Hoobler’s team had to answer specific questions about where objects may have been located in relation to each other and how they may have appeared. Such questioning may reveal gaps in knowledge as well as new insights.Given that the 3D modeling process is recognized as a site of learning for research, it makes sense that it can serve as a teaching tool as well. Engaging with models on Sketchfab gives students a chance not only to view physically distant structures and objects but also to manipulate them through zoom, rotation, and pan functions, and to gather context through annotations. Paired with print and other static sources, 3D models can help students form connections between textual descriptions and visualizations. Having the chance to build in 3D takes this learning to another level. Hoobler’s collaborators were students who not only contributed directly to the project’s scholarship but also learned 3D modeling in order to make those contributions. By learning to look at and build 3D models, students can develop their skills in close looking while also gaining technical experience.One example of how SketchUp can support 3D modeling as pedagogy can be found in the hands-on exercise in close looking presented in a tutorial developed in the Digital Art History and Visual Culture Research Lab at Duke University. The tutorial focuses on a small but complex architectural feature: the portal of the former church of Santa Margherita in Venice.16 The portal, and indeed much of the church building itself, no longer exists, but a scale drawing published by Antonio Visentini offers visual evidence. The tutorial asks students to use this drawing to construct a 3D model of the portal, an activity designed so that they must engage with the portal’s period and style as well as with the technical tools needed to create a digital 3D model.SketchUp offers a variety of tools that make this tutorial possible. Students can import the 2D drawing directly into SketchUp and work with it at scale to trace aspects of the portal and then build them out in 3D. As they work, they must make decisions about how they measure and draw each of the portal’s components. This decision-making process requires them to zoom in on many of the portal’s details to get a closer look. This looking reveals aspects of the portal that may not be immediately apparent—for example, that the columns are engaged with the pilasters. SketchUp’s 3D Warehouse (and now Sketchfab’s online store) offers standard components such as Corinthian capitals that students can use rather than attempting to model their complexity, and its “Follow Me” tool lets students trace and extrude details such as molding that may at first appear complicated. The resulting model offers digital and visual evidence of the students’ learning: their model represents both what they have seen in the 2D drawing and the skills they have learned by using SketchUp’s tools, which they can now apply to other projects.Using Sketchfab, students may then annotate their model, as the Arc/k Project and Iconem have done, directly embedding their own evidence-based observations within the model scene, and then share their model, itself a kind of scholarly argument. Through their annotations, students can guide their viewers through the decision-making processes that went into the model’s creation; highlight important spatial, structural, or stylistic relationships within the model; and ask viewers to consider specific elements of the model. This in-depth tutorial provides students with the skills they need to build their own models based on historical documentation. It introduces them to many of the tools in SketchUp and demonstrates how they can use those tools together to build and organize a model.Although I began this review by highlighting aspects of both SketchUp and Sketchfab that make them relatively easy to use, I want to emphasize two important points about the idea of “easiness” as it relates to learning and using digital platforms for humanities research. First, as Paige Morgan has discussed, a skill that may seem easy to one person is often challenging to another; the ease with which individuals acquire 3D modeling skills is a product of their prior knowledge and contexts, the availability of training support, and the information available in primary sources and their conditions.17 Second, even with their comparatively simple interfaces, SketchUp and Sketchfab have the potential to support in-depth, complex, and sophisticated modeling practices, as the examples I have provided demonstrate.Potential users of both SketchUp and Sketchfab also should be aware of several possible limitations of the platforms. First, as noted above, both are proprietary, meaning that some features are available only behind their respective paywalls. Both have been monetized for their audiences; their code is either not available for reuse and extension (SketchUp, though users can build extensions using the Ruby coding language) or can be accessed only through high-priced developer accounts (Sketchfab). Both also offer free account options and significant discounts on paid tiers for educators and students, and they require only access to a computer and an Internet connection. Given the persistent digital divide, what Daniel Greene has argued should be reconsidered as the “access doctrine,” a common belief that technology and technical skill building can reduce poverty, such requirements can still be limiting for some educators.18 However, they are far less burdensome than the high-powered computing requirements of many other modeling platforms, which are built on many of the same digital modeling principles. Open-source alternatives to SketchUp and Sketchfab include Blender and JavaScript libraries such as Babylon.js.19 Many scholars prefer working with open-source tools precisely because the code behind those tools is made available for reuse and augmentation, often with no purchase required. Furthermore, academically built and sustained projects such as MorphoSource offer alternatives to Sketchfab that prioritize research and preservation.20 Sketchfab, it must be emphasized, should not be relied on as a platform for preserving digital 3D models; rather, it should be used only as a communication platform, given that at some point it may require a paid subscription that some users may not be able to maintain over the long term. Furthermore, when planning for preservation, researchers should always consider with caution the stability of proprietary, corporately supported software, whose stakeholders’ goals may differ from theirs. If scholars wish to preserve their models, they must work with institutional repositories and projects like MorphoSource, whose explicit goals include long-term preservation of digital cultural heritage.Despite such drawbacks, there is value in engaging with both SketchUp and Sketchfab. Both platforms offer important tools to support research and teaching in architectural history through modeling and close looking. Indeed, they offer sites for important decision-making processes to play out as scholars consider what they hope to represent, how it can and should be represented, and why a particular 3D model is crucial to their research. In both spaces, scholars and students alike can undertake complex projects that can enable avenues for study that significantly supplement 2D media. While it may take time to learn SketchUp and Sketchfab, or any other 3D modeling and viewing tools, it may be well worth the effort and may encourage scholars and students to think and look in ways they might not otherwise have considered.