The University of Chicago made a site occupied by tennis courts available to the Manhattan District on a one dollar lease, for the construction of a new chemistry building with of space. Stone and Webster commenced work on this in September 1942 and it was completed in December. It was soon found to be too small and an adjacent plot was added to the lease, on which a annex was built and completed in November 1943. Extensive work was then carried out on the ventilation system to allow the laboratory to work with plutonium more safely. A site containing an ice house and stables owned by the University in Chicago was made available in April 1943. Known as Site B, it was remodeled to provide of laboratories and workshops for the health and metallurgy groups. The 124th Field Artillery Armory was leased from the state of Illinois to provide more space in March 1944 and about of space was leased or built, at a cost of $2 million.