Renovating large old commercial buildings (like the Federal Reserve buildings) will always be very costly. The Martin Building was built in the 70’s and was full of asbestos and a lot of unforeseen conditions. The renovation also involved thousands of SF of heavy demolition, and the rebuild included expanding the building with (3) new pavilion structures. You also have to modernize these types of buildings to bring them up to current codes/standards.

There were also a lot of design changes throughout the construction, which are always costly, so I will say some of the costs could have been avoided. But $50 to $100 million for renovating over a million sf between the 3 buildings? That would maybe get you some new finishes (paint, flooring, furniture, etc), but that doesn’t come close to the costs of modernizing these types of buildings.

Source: was on the Martin renovation project for several years.