Riga is situated on the Baltic Sea coast on the mouth of the River Daugava. The largest city in the Baltic states serves as a major cultural, educational, political, financial, commercial and industrial center. The Historic Centre of Riga has been declared a UNESCO World Heritage Site, and the city is particularly notable for its extensive Art Nouveau (Jugendstil) architecture.The Doma Cathedral is considered the largest church with a magnificent organ from 1844. Riga Castle (Rīgas Pils), which houses the Museum of Latvian History and the Museum of Foreign Art and churches like the St. Peter's Church, with its 123 m high tower, St. John's Church, a small 13th-century chapel, behind St. Peter's Church are the main religious sights. Important to visit is the Powder Tower (Pulvertornis), the only tower that remains from the city wall with The Latvian Museum of War inside.