In the main building of ETH Zurich, the architectural and educational concepts of three generations of architects and university educators overlap and contradict each other, from the Semper Building to Gulls Polytechnic and Charles-Edouard Geisendorf's renovations in the second half of the 20th century. Spaces, sequences of spaces, lighting, access, and surfaces are currently defined by the densifications of the 1960s and 1970s. Given the varying demands that will be placed on the main building in the future, short-, medium-, and long-term strategies for preserving and restoring qualities in the heterogeneous structure are necessary. Under the leadership of Uta Hassler, projects have been designed and partially implemented for core areas of the "Poly" - stairs, corridors, the dome hall, administration offices, and the auditorium.