The White Tower, the landmark of Thessaloniki, was once the south-east tower of a large fortification. Ιt was probably built in the fifteenth century after the conquest of Thessaloniki by the Turks, to replace a Byzantine tower. Throughout its long history the tower's name and use changed several times. In the 19th century it was used as a long-term convict prison. In 1890, a convict whitewashed the tower's walls in exchange for his freedom, hence the name 'White Tower'. Today there is an exhibition in the tower about the city’s history.