Le Maitre was born in the French city of Toulouse, but left France in 1773 to come to Brunant. He settled down in Dortmund and helped design a few buildings in Koningstad Centrum. In 1788 he was chosen to renovate Koningsberg Palace so it could house Brunant's Congress. While the Carrington administration wanted a simple fix-up of the palace, Le Maitre envisaged a grand redesign meant to rival the palaces of Europe. While working on the Koningsberg Palace, he also worked on the Realpaleis.
With costs rising dramatically (Th. 30,000,000 had been spent by 1794), he was fired in 1797 and replaced with a more frugal architect. Le Maitre was fined by the government for his excesses and lived in poverty until his death in 1810. However, his mark on the palace still remains (the Senate Chambers is a good example) and he is still considered the main architect of the plan.