St. John's Cathedral was completed in XVth century. One can admire work by Wit Stwosz - one of the most famous Polish artists. St. John's Cathedral was originally a parish church and only became a cathedral in 1798.

Many important events took place in this cathedral including coronation of Stanislaw August Poniatowski in 1764 and the swearing of the Sejm (Polish parlament) to uphold the 1791 constitution.

St John’s claims to be the oldest church in Warsaw. Although a major church in the Mazovian Gothic style, completed in the 15th century, St John’s was only upgraded from a parish church to a cathedral in 1798. Destroyed during World War II, is has been reconstructed in its original style and features major Gothic art works by Wit Stwosz. The cathedral was used in 1764, for the coronation of the last Polish king (Stanislaw II) and for the swearing in of the Sejm (Polish Parliament) after the constitution of 1791. The covered footbridge connecting it to the Royal Palace was the result of a failed assassination attempt on King Zygmunt III. The interiors of Cathedral feature multiple works of religious art, tombs and various sculptures and paintings.

The Baryczkowski Crucifix from Nurnburg is renowned for the expressiveness on the face of the crucified Christ. Also see the red marble Renaissance tombs of the last Mazowian dukes and the tombs downstairs in the crypt that include the resting place of Nobel Prize winner Henryk Sienkiewicz.