The Cathedral of St. John the Baptist in Wrocław,, is the seat of the Roman Catholic Archdiocese of Wrocław and a landmark of the city of Wrocław in Poland. The cathedral, located in the Ostrów Tumski district, is a Gothic church with Neo-Gothic additions. The current standing cathedral is the fourth church to have been built on the site.
A first church at the location of the present cathedral was built under Přemyslid rule in the mid 10th century, a fieldstone building with one nave about 25 m (82 ft) in length, including a distinctive transept and an apse. After the Polish conquest of Silesia and the founding of the Wrocław diocese under the Piast duke Bolesław I Chrobry about 1000, this Bohemian church was replaced by a larger basilical structure with three naves, a crypt, and towers on its eastern side. The first cathedral was however soon destroyed, probably by the invading troops of Duke Bretislaus of Bohemia around 1039. A larger, Romanesque-style church was soon built in its place in the times of Duke Casimir I, and expanded similar to Płock Cathedral on the behest of Bishop Walter of Malonne in 1158.
After the end of the Mongol invasion, the church was again largely rebuilt in the present-day Brick Gothic style. It was the first building of the city to be made of brick when construction of the new choir and ambulatory started in 1244. The nave with sacristy and the basements of the prominent western steeples were added under Bishop Nanker until 1341.
On June 19, 1540, a fire destroyed the roof, which was restored 16 years later in Renaissance style. Another fire on June 9, 1759, burnt the towers, roof, sacristy, and quire. The damage was slowly repaired during the following 150 years. Between 1873-75, Karl Lüdecke rebuilt the interior and western side in neogothic style. Further work was done at the beginning of the 20th century by Hugo Hartung, especially on the towers ruined during the 1759 fire.
The cathedral was very badly damaged (about 70% of the building) during the Siege of Breslau and heavy bombing by the Red Army in the last days of World War II. Parts of the interior fittings were saved and are now on display at the National Museum in Warsaw. The initial reconstruction of the church lasted until 1951, when it was reconsecrated by Archbishop Stefan Wyszyński. In the following years, additional aspects were rebuilt and renovated. The original, conical shape of the towers was restored only in 1991.
The cathedral holds the largest pipe organ in Poland, built in 1913 by E.F. Walcker & Sons of Ludwigsburg, Baden-Württemberg, Germany, for the Centennial Hall — formerly the largest organ in the world.