The historically significant Daniel Guggenheim Building was completed in 1928 and is the home to Caltech’s Graduate Aerospace Laboratories. While honoring the historic nature of the building, we performed a major seismic reinforcement, added a new stair to connect the second and third floors, reconfigured existing double-height spaces and performed a full upgrade to mechanical, electrical, plumbing and fire life safety systems. The 33,000 SF interior renovation produced new laboratories, conference facilities, entrance lobby and administrative offices. These upgrades, along with new glazed walls and windows, greatly enhanced the building’s desirability among students and researchers.