The Museum of the History of Architecture of St. Sophia Cathedral in Polotsk is a branch of the National Polotsk Historical and Cultural Museum-Reserve. The museum’s exposition is housed in St. Sophia Cathedral, an architectural monument from the mid-11th to the mid-18th centuries. The museum was opened to visitors in 1987. Museum exhibits tell about the history of architecture of the most ancient stone building on the territory of modern Belarus, about numerous reconstructions, repairs and the last restoration of the monument. In the St. Sophia Cathedral you can see fragments of masonry of the 11th century, the almost completely preserved ancient foundation, as well as fresco paintings of the late 11th century, one of the oldest in Belarus. The concert hall in St. Sophia Cathedral was opened in 1983, designed for 304 seats. Thanks to its unique acoustics, a chamber music concert hall was opened here, which became known far beyond the city limits. In 1985, specialists from the Czech company “Rieger Kloss” installed an organ produced according to an individual project, which organically joined the museum's exposition of an architectural monument and attracted numerous music lovers. The International Festival of Ancient and Modern Chamber Music (April) and the International Festival of Organ Music "Zvani Safіі" (November) are annually held in the concert hall. Traditionally, on Sundays, organ concerts are performed by the soloist of the concert hall, laureate of the international competition Ksenia Pogoreloy. Annually, over 300 concerts of organ and chamber music are held in St. Sophia Cathedral.