As the third largest city in Bulgaria and one of the country's most attractive towns, Varna is known as Bulgaria's 'Seaside Capital' and the 'Pearl of the Black Sea Coast'. The town is arranged in tiers along the curve of Varna Bay, and besides being a popular beach resort, it rivals the important cities of Sofia and Plovdiv in its wealth of museums, art galleries, historical buildings and cultural entertainment, and as such is a year-round holiday destination. The 19th-century Cathedral of the Assumption of the Virgin is an impressive landmark, while the extensive ruins of the Roman Spa in the centre of town constitutes the largest ancient building in Bulgaria, dating back to 1700. It is the main port for commercial and naval shipping and has a casual, cosmopolitan atmosphere with a Mediterranean charm created by the sunny climate, calm sea, beach promenades and red-tiled roofs. Varna is the gateway to the nearby beach resorts, including Albena and the mega-resort of Golden Sands, and numerous scenic spots along the coast are within easy reach, such as the nature reserve at Kamchia and the crumbling rock formations and dramatic cliffs along the Balchik coast.