St. John's Archcathedral in Warsaw

The Cathedral of the Holy Spirit in Warsaw is the main temple of the Polish Catholic Church in Poland, located at 2 Szwoleżerów Street. It was originally built as a military Orthodox church, and its history is marked by controversy regarding its construction date and patronage. Some researchers, such as Piotr Paszkiewicz, date its origin to 1867, identifying St. Olga as its patron saint and interpreting its construction as part of Russian political strategy. Others, like Kirył Sokoł, date the church to 1903–1906 and attribute its patronage to St. Martinian. After being abandoned by the Russian military in 1915, the building stood vacant for four years before being handed over to the Catholic Church, and since 1945, it has been under the care of the Polish Catholic Church. Architecturally, the cathedral takes the form of a Greek cross, featuring an octagonal drum topped with a lantern. Its design blends Greek and Neo-Romanesque stylistic influences, while its modest decorations evoke the aesthetics of early Christianity. The interior was originally adorned with an iconostasis, frescoes, and icons, including a unique depiction of St. Martinian. Today, the marble altar and fragments of the frescoes remain, complemented by modern stained-glass windows. Interestingly, the temple has retained many of its original architectural features, and annual services held in honor of fallen light cavalry soldiers (szwoleżerowie) recall its pre-war purpose. The cathedral also serves as a memorial site associated with the 1st Józef Piłsudski Light Cavalry Regiment.