Karlovy Vary (Czech pronunciation: "karlovy vary" German: Karlsbad, formerly also spelled Carlsbad in English) is a spa city in the Karlovy Vary Region of the Czech Republic. It has about 46,000 inhabitants. It lies on the confluence of the rivers Ohre and Teplá. It is named after Charles IV, Holy Roman Emperor and the King of Bohemia, who founded the city. Karlovy Vary is the site of numerous hot springs (13 main springs, about 300 smaller springs, and the warm-water Teplá River), and is the most visited spa town in the Czech Republic. The historic city centre with the spa cultural landscape is well preserved and is protected by law as an urban monument reservation. It is the largest spa complex in Europe. In 2021, the city became part of the transnational UNESCO World Heritage Site under the name "Great Spa Towns of Europe" because of its spas and architecture from the 18th through 20th centuries.