Modernist architecture of the 20th century, including especially objects classified as monuments, has more and more proponents and epigones. Many members of society still do not treat them as a valuable part of the cultural and social heritage, particularly when modernist architecture is underinvested or derelict. For others, the architecture of this kind is an essential element of urban identity and image in many parts of the world. Thus, it is worth identifying the actual value of modernist 20th-century architecture, especially in Poland and other Central and Eastern European countries, where such objects entail connotation with the communist past. We believe this value is changing from the perspective of today's and future generations. However, identifying such a value, specifically in its economic and monetary dimension, is still a challenge. It requires an analytical and scientific dialogue. Hence, we suggest discussing an appropriate approach to estimate the ambiguous value of modernist heritage. Based on a review of existing classifications of heritage value, as well as valuation methods, we propose a three-stage valuation procedure to capture the value of the 20th Century Post-Socialist Train Stations in Warsaw.