At the meeting point of the eastern wall and the sea wall, stood a Byzantine tower, on the site of which, in the late 15th century, the White Tower was erected. It was constructed as part of a programme of modernization of the city’s fortifications by the Ottomans (cf. Alysseos Tower). The emblem of Thessaloniki, the White Tower is intimately connected with the city’s history and the focus of many legends reflected in its various names. The original appellation Fort of Kalamaria (18th century) was replaced in the 19th century by the names Tower of the Janissaries and Tower of Blood (Kanli Kule), referring to the use of the building as a prison for long term convicts and those sentenced to death, whom the Janissaries executed on the battlements, dyeing with blood the exterior walls of the tower. In 1890, the tower was whitewashed by a convict in exchange for his freedom, and was henceforth known by its current name, the White Tower. As a defensive structure, it is a characteristic example of the great circular towers of the late 15th and early 16th centuries, which replaced the mediaeval rectangular structures, reflecting the need to defend against the new and widespread practice of artillery warfare, which led to a variety of innovations in defensive architecture. The structure was topped by a conical, wooden roof, covered in lead. Until the early 20th century, a polygonal defensive structure survived at the base of the tower, with apertures for cannon at sea level along the sides and small towers serving as look out points at the corners of the enclosing wall. This complex was constructed in 1535-36, according to the Turkish inscription found above the entrance. Inside the White Tower, there is now a museum where visitors can enjoy a digital reconstruction of the city’s history.