Ostrov consists of 12 municipal parts (in brackets population according to the 2021 census):[2] The original name of the first settlement was Zlaukowerde (meaning "Slauko's island"), which changed into the German name Schlackenwerth.

The town lies at the confluence of the Bystřice River and the creek Jáchymovský potok; the Ohře flows just outside the territory of Ostrov.

[3] Today's appearance of the old town was determined mainly by construction activities after the last great fire in 1866.

From the 19th century to 1918, Ostrov belonged to one of the branches of the imperial House of Habsburg, the Grand Dukes of Tuscany.

[3] After World War I, being located in the historic region of Bohemia, Ostrov became part of newly established Czechoslovakia, although it had a German majority and only 7% of the Czech population.

At the beginning of World War II, during the occupation of Czechoslovakia by Nazi Germany, the Czech population was forced to leave the town.

The population of Ostrov then multiplied as people were moved to work in the uranium mines in nearby Jáchymov.

[3] The extensive housing blocks from the 1950s forming the new part of Ostrov are considered one of the best examples of socialist realism architecture in the Czech Republic.

The Palace of Princes serves as the town library, its Václav Havel's Orangery is used for exhibitions and concerts.

[15] The parish Church of Saint Michael and Mary, the Virgin Most Faithful dates from the late 13th century.

Today it is a national cultural monument and, since 2019, it has been a UNESCO World Heritage Site as a part of the Ore Mountain Mining Region.