Mariánské Lázně is a spa town in Cheb District in the Karlovy Vary Region of the Czech Republic. It has about 13,000 inhabitants. The town, surrounded by green mountains, is a mosaic of parks and noble houses. Most of its buildings come from the town's Golden Era in the second half of the 19th century, when many celebrities and top European rulers came to enjoy the curative carbon dioxide springs. The town centre is well preserved and is protected by law as an urban monument zone. In 2021, the town became part of the transnational UNESCO World Heritage Site under the name "Great Spa Towns of Europe" because of its famous springs and architectural testimony to the popularity of spa towns in Europe during the 18th through 20th centuries.