To build the foundation for these works, the Corps had to pour an 8-foot-thick concretefoundation underwater in the middle of one of the busiest shipping lanes in the world.
The design featured a wooden frame on top of a concrete-slab foundation, with an exterior covered in gray asbestos shingles. (Steel was in short supply.) The structure violated the Cambridge fire code, but it was granted an exemption because of its temporary status.