Paşazade Mehmet Memduh Bey as Mülki İdadi building on Rebiül - evvel 12th 1310 in accordance with Islamic Calendar (October 5th 1892 Gregorian), is still in Sivas Museum. The building, which is one of late Ottoman Period civil architecture samples of 19th century, has three floors and an internal courtyard. The main material is stone in its external sides an wood in the internal places.
The building, which has been assigned as official headquarters for a period of three and a half months to Mustafa Kemal Atatürk and his friends has gained a historical identity since Sivas Congress meetings have been held here, the National Struggle in Anatolia has been organized here it has been proved to the whole world that the public will is over any kind of constraints and personal and class management and the bases of Republic Management have been laid there.
Thirty two members representing nineteen cities have participated Sivas Congress, but due to the delegates elected from the cities and participated the congress later, these numbers show variance.
The building, which continued the function of a school building since the date of its construction, has been called with the names İdadi, Sultani, Sivas High School, Congress High School. In a repair performed in 1930, the main entrance on the eastern side has been moved to the western side and the roof has been covered with steel sheet.
The building, which has served as a high school until 1981, has been planned to be converted into a museum upon the directives of the President Kenan Evren. In 1984, the Congress Building has been transferred to the Ministry of Culture and Tourism and as the result of the restoration, exhibition and arrangement works started in the same year by the General Directorate of Ancient Works and Museums of our ministry, the basement has been arranged as the places where the warehouses, laboratory and photograph room are located, while the ground floor is arranged as the Ethnography Museum and the upper floor is arranged as Atatürk and Congress Museum.

In the show hall of the building, which has been used as a headquarters for some time by Mustafa Kemal Atatürk and Representation commission, the meetings of Sivas Congress have been held between the dates September 4th - 12th 1919. The Historical Congress Hall and the resting and study room belonging to Atatürk are kept in the conditions that were existent on the days during which the congress was held.

In the upper floor, the hall where the notifications and circulars relating to the events before the congress, the congress preparation of Mustafa Kemal Atatürk; the telegraph room constituting the base of the communication of that time; the hall where the minutes of Sivas Congress are kept; the documents including the notifications and news relating to Anatolian Women Country Defense Association whose center was established in Sivas and the printing machine with which İrade - i Milliye Newspaper was printed and the halls, where volumes of this newspaper are exhibited, are located.
Documents belonging to all decisions taken in Sivas during and after Sivas Congress, Presidency Mansion - Atatürk Special Archive, Special Archive of General Staff Presidency Military History Commission and attaché, the samples of the documents in the archives of Atatürk Research Center Presidency are exhibited in the museum.