The Jorge Machado Moreira building, designed to house the National School of Architecture, is a renowned Brazilian modern heritage site. In addition to its architectural and spatial quality, it presents materials and construction details of great substance. Although the architectural community recognizes its significance since conception, with an award at the IV São Paulo Biennial in 1957, the building itself only received legal protection and heritage perception in 2016, after an alarming fire episode. To preserve the built heritage characteristics, in-depth knowledge of its current state of conservation is essential. This investigation uses a two-stage methodology to assess the progression and severity of the main issues affecting its structural health: (i) a documentary review, based on historical data of its design and on two technical reports regarding its state of conservation; and (ii) a qualitative analysis of the main damages and their progression over time. The aging of the materials, associated to the lack of conservation, as well as the changes in use and inadequate maintenance led to the deterioration of structural systems, sealing and coatings. The visual analyses carried out in the past years, associated with the previous reports, certified the predominance of exposure and corrosion of the steel-reinforcement in concrete elements, the loss of coating mortar, the detachment of ceramic finishings, and propagating cracks in several structural and non-structural elements. Also, these symptoms worsened over the years, emphasizing the need for effective monitoring, identification of key problems, cost-efficient restoration solutions suitable for the Brazilian context, and most of all an urgent need for (preventive) conservation policy.