The building of the museum was originally designed by the architect Ludwig Lange but his plans were partially modified by Panages Kalkos and later, by Harmodios Vlachos and Ernst Ziller, who completely rearranged the facade and changed the plan of the east wing and the central hall. Two additions were made on the east side of the building; a new wing was constructed in the early 20th century based on the plans of Anastasios Metaxas and a two-storeyed building, designed by G. Nomikos, was erected in 1932-39.