The historic core of Prague is a monumental record of the city's one thousand year development, and was named an Urban Memorial Reservation for its Historic, Cultural, Architectural and Urban merits, which include almost 2000 cultural monuments. In 1992, Prague was entered into the UNESCO World Cultural Heritage List. The city of Prague, which like medieval Rome was built on five hills, lies on both banks of the Vltava River, enveloped in the magic of its glorious and tragic past. Since the early Middle Ages, it has been known as one of the most beautiful cities in the world. In the 14th century, Prague was a cosmopolitan city which surpassed all other central European towns. The Vltava river was already spanned by the Stone Bridge, which is still among its greatest architectural treasures.