The White Tower of Thessaloniki is a landmark and historical monument located in the city of Thessaloniki in Greece. The tower, also known as the "Lion Tower," was built in the 15th century as part of the city's fortifications and was used as a prison and place of execution during the Ottoman period.

The White Tower is situated at the waterfront of Thessaloniki's Old Town and has a height of about 34 meters. The tower has six floors and is made of stone. It is octagonal in shape and has a diameter of 23 meters at the base.

During the Ottoman period, the tower was used as a prison and torture chamber, and it is estimated that thousands of people were imprisoned and executed there. It was also used as a watchtower and a lighthouse to guide ships into the port.

In the early 20th century, the tower was restored and converted into a museum dedicated to the history of Thessaloniki. The exhibits include archaeological artifacts and historical documents that illustrate the city's rich and diverse history. Visitors can also climb to the top of the tower to enjoy a panoramic view of the city and the sea.

Today, the White Tower is one of the most popular tourist attractions in Thessaloniki and is an important symbol of the city's history and culture.