The mansion which today serves as the Museum of Trabzon was constructed by the money broker Kostaki Teophylaktos around 1898-1918 in the early 1900s. The architect of the mansion is supposed to have been an Italian, however his name is not clarified. The structure reveals that most of the materials used in the construction of this mansion were imported from Italy.

In 1917, Kostaki Teophylaktos went bankrupt, and all his property including this mansion was confiscated. Later the Nemlioğlu Family bought the mansion.

When Atatürk visited Trabzon he and his wife Latife had stayed in this mansion15-17 September and around 1927-1932, the mansion was expropriated while Ali Galip Bey was the governor of Trabzon. It served as the courthouse between 1927 and 1931, and as the inspectorship building between 1931 and 1937. The building was appropriated to the Ministry of Education in 1937, and used as the Vocational School for Girls for 50 years. The mansion is one of the best civil architectural buildings in Turkey. Except its basement, all its walls were hand painted.

Between 1988 and 2001, the mansion was re-stored under the supervision of the Ministry of Culture and Tourism and opened to visitors as a museum on April 22, 2001.

The basement of the mansion is the section for archaeological artifacts. The ground floor is designed for exhibition of the mansion. Ethnographical artifacts are displayed on the first floor. Museum Administration is on the second floor.