The city's 13th century Castle, probably built by Kęstutis to defend the road to Trakai, was the country's first defensive bastion and the only double-walled castle in Lithuania. The surrounding walls were initially over two metres wide and 13m high. Unlike most other castles of the time this one was made of stone, not wood. However, in 1362, after a siege, the Teutonic Knights managed to destroy it, although local legend has it that the Castle was not destroyed and that 36 survivors remained. These survivors along with the Knights are allegedly still burning in an eternal fire which can only be extinguished by an innocent person entering the Castle via a secret cave. However, history books dictate that it was destroyed and its replacement, some of which can be viewed at the site today, was built by 1368. The Castle has been modernised with sleek glass windows enclosing the top, and is sometimes home to art exhibitions. The building recently received a 1.16Lt million facelift, which included the restoration of several architectural elements as well as the construction of a traditional wooden bridge over the former moat.