Until 1596, Kraków was the capital of Poland. Situated on the Vistula River, the city has traditionally been one of the leading centers of Polish cultural life. The current plan of the Old Town (Stare Miasto) was laid out in the 13th century and features a Main Square (Rynek Główny), which is the largest medieval town square in Europe. At the center of the square is the Renaissance Sukiennice (Cloth Hall), which houses the National Museum art gallery. Just south of the Old Town, the hilltop Wawel Royal Castle was the seat of Polish kings for 500 years. Kraków makes a fine base for day trips, including the remarkable Wieliczka Salt Mine, the tour of which culminates in a massive underground church carved entirely from salt. The notorious Nazi concentration camps of Auschwitz and Birkenau are also a short distance from Kraków. Visiting them is upsetting, of course, but doing so provides a visceral sense of the enormity of the Holocaust that is difficult to gain from a book or film.