Marchegg’s remarkable parish church is dedicated to St. Margaretha and dates from 1268 when it was constructed on the orders of Přemysl Otakar II. The long choir, with its steep saddleback roof, is one of the most beautiful early Gothic buildings in Austria. The church was extended between 1789 and 1790 by the addition of a Baroque nave. The high altar dates from 1660 and the church has a side altar created by members of the Vienna Secession Movement in 1909. An early 15th century bell, which survived the Turkish invasion of Austria, can be found in the 19th century church tower.