Cathedral of the Immaculate Conception of the Blessed Virgin Mary in Siedlce. A brick church in the neo-Gothic style with a Latin cross plan according to the design of the provincial architect Zygmunt Zdański. Built in the years 1906–1912, at the initiative of Father Józef Scipio del Campo on a square donated by Ludwik Górski on behalf of the Land Credit Society. Consecrated on September 21, 1913 by Franciszek Jaczewski, Bishop of Lublin. Cathedral since January 25, 1924 by a papal bull of the Holy See. Finally finished in 1928 at the initiative of Father Julian Ryster from donations from the clergy and faithful on the occasion of the 10th anniversary of the resurrection of the diocese. In 1928 Dominik Biernacki completed the construction of the organ, which he had begun in 1914. During World War II, the stained glass windows were destroyed, later restored. The church underwent a thorough renovation in 1997–1998 (before the pilgrimage of Pope John Paul II in 1999, during which he visited Siedlce), when the presbytery was restored (replacement of the floor, transfer of the tabernacle) and a new stained glass window was made in the central window of the pediment.