The objective of this work is the elaboration of a methodology to develop STEAM projects (Science (S), Technology (T), Engineering (E), Art (A) and Mathematics (M)). The methodology proposed in this article is part of the results of the project ERASMUS+DART4City (2020-1-ES01-KA227-SCH-095545) “Empowering Arts and creativity for the cities of tomorrow”, whose objective is to design a methodology in order to develop STEAM projects from European curricula. The proposed methodology emerges after analysing, among others, the curricula from Spain, Italy, Cyprus, France, Finland and Germany, taking into account the international perspective of STEAM education, their priorities and problems. The proposal has two variants: “forward” and “backward”. Both variants begin with the analysis of the curriculum in which the contents are grouped by similarity, classified according to STEAM disciplines so that the thematic areas can be obtained. Subsequently, in the “forward” variant, the thematic areas with most connections are selected as areas of opportunity; for the development of the STEAM project, so from the “forward” methodology, the teacher will be able to select an area of opportunity and develop the project around it, so, the concept or project idea comes from an area of oportunity. The “backward” variant starts from a concept considered interesting for society or just for the teacher and which will become the main theme of the STEAM project and, from that concept, we will select the thematic areas of the curriculum that can be included in the project. The main difference bewteen both methodologies is that in the “forward” variant, the STEAM project concept comes from an area of oportunity detected in the curriculum meanwhile in the “backward” variant the concept of the STEAM project comes from the teacher, without taking into acount, initially, the curriculum. This article shows an example of application of each variant. From the “forward” variant, the STEAM project “Sustainable City” is shown for years 4, 5 and 6 of Primary Education, which has been carried out from the opportunity area “Sustainability”. From the “backward” variant, we develop the STEAM project, whose main theme is cooking, in which, based on this theme, 10 tests are developed, each of them related to different thematic areas of the Spanish curriculum.