Budapest (pronounced/ˈbuːdəpest/ (AE), also /ˈbju-/ (BE) or /ˈbʊ-/; Hungarian IPA: ['budɒpɛʃt]) is the capital city of Hungary and the country's principal political, cultural, commercial, industrial and transportation centre. The official language spoken is Hungarian. Budapest became a single city occupying both banks of the river Danube with the amalgamation on 17 November 1873 of right-bank (west) Buda (Ofen in German) and Óbuda (Old Buda or Alt-Ofen) together with Pest on the left (east) bank. Aquincum, originally a Celtic settlement, was the direct ancestor of Budapest, becoming the Roman capital of Lower Pannonia. Magyars arrived in the territory around 900. Their first settlement was pillaged by the Tatars in 1241-42. The re-established town became one of the global centers of humanist culture in the 15th century. Following nearly 150 years of Ottoman rule, development of the region entered a new age of prosperity in the 18th and 19th centuries, and Budapest became a global city after the 1873 unification of its three constituents. Regarded as one of the most beautiful urban landscapes in the world, Budapest is considered an important Central European hub for business, culture and tourism. It is home to both the Central European University and the CEU Business School. Its World Heritage Sites include the banks of the Danube, the Buda Castle Quarter, Andrássy Avenue and the Millennium Underground railway, the first on the European continent. Budapest attracts over 20 million visitors a year, making it one of the top destinations in Europe. It is now also the third most popular destination in the world for luxury weekend getaways, and its Gellért Spa was named the third best thermal bath in the world. Budapest's level of development surpasses the EU average, currently standing at 125 percent.