The Austrian architect Emil von Foerster won the international architectural competition for mineral baths with a hotel which was held as early as 1889. The hotel construction hardly commenced when it had to be suspended (in 1893) due to shortage of funds. Later in 1904, the architects Petko Momchilov and Friedrich Gruenanger introduced more clarity to the conceptual design for the modern-day appearance of the complex. The Sofia Mayor signed in 1906 a contract with P. Momchilov for the developement of a detailed design for a larger and smaller bathrooms. The artist Haralampi Tachev contributed the decorative facade drawings of plants and geometric patterns in the then modern Art Nouveau style (1908, also known as Secession) . The ceramic images of Apollo Medicus - god of health and the goddess Tyche - patroness of towns - were placed on the sides of the main entrance of the building using a technology, which Prof. Stefan Dimitrov provided. The stone sculptures are the work of the artist Georgi Kiselinchev.
The smaller bathroom opened in 1908, while the larger one - featuring two swimming pools, family bath tubs, Turkish-Roman baths – on 1st (13th) May 1913; a health care institute with water-filling facilities opened in the north wing (1914).
The smaller bathroom was demolished during the Sofia bombing(1944), and portions of the larger one were seriously affected. Following the World War II the larger bathroom was renovated just as it was originally and declared a cultural monument of local importance (Izvestiya Newspaper, issue No. 73/1955). The building was closed to visitors in 1986due to its poor condition and subsequently completely abandoned after 1989.
The Sofia Municipality undertook repairs to the roof in 1996 and agreed to rehabilitate the building at its own expense as the only way to preserve it, and in the future - to make it an outstanding municipal building that would house the Sofia History Museum as the latter needed a site for its permanent exhibition. In 1998 the building was declared an architectural and artistic monument of national importance (SG, issue No. 25/1998). The Sofia Municipality held a national competition during the same year for the ‘Adaptation of the Municipal Mineral Bath House for a Museum of Sofia with an Active Presence of Mineral Water’ – a team led by the architect Stanislav Konstantinov won the competition. The first stage of rehabilitation works was financed under the Beautiful Bulgaria Program (2004) - walls, multicolored majolica using original formulas and molds; water-filling spouts were built to ensure free mineral water in the neighborhood between the Ekzarh Yosif Str., Iskar Str. and Serdica Str. In 2006 the Sofia Municipal Council decided to build a SPA center, incl. two swimming pools, instead of the previously approved second phase for a museum area. The Museum was left with the western and southern ends of the building, main lobby and two of the four courtyards (total floorage area ~ 7000 sq. m). The final stage of the conservation, restoration and adaptation of the building was completed in the period 2007-2013 under the Operational Program ‘Regional Development’ of the European Commission and the Ministry of Regional Development and Public Works.
The striking image of the Municipal Central Mineral Baths impresses with its powerful multiwing composition, complex roofing system, and rich Art Nouveau (Secession) decoration of the facades. A unique picturesque ensemble is formed along with the garden in front of the Baths and the adjacent historic buildings dating back from different times. The extended archaeological site nearby also adds to the appearance of the historic center of the Capital and makes the Baths building appropriate to house the SofiaHistory Museum.
