In St. Petersburg, Thomon built the Stock Exchange (1805-1810; now the Central Naval Museum), one of the most important monuments of Neo-classicism in Europe. It is a great barrel-vaulted hall covered by a pitched roof. The gable end is pierced by a huge semicircular window, picked out by radiating brick voussoirs. The rectangular building is surrounded by a peripteral order of unfluted Doric columns, which are based on those of the archaic Temple of Poseidon at Paestum. The interior is lit by an upper row of smaller segmental windows on the long sides. He also laid out the surrounding area at the tip (strelka) of the Vasily with granite quays and ramps, siting a pair of rostral columns there to serve as lighthouses.