The Wawel Cathedral has been the main burial site for Polish monarchs since the 14th century. As such, it has been significantly extended and altered over time as individual rulers have added multiple burial chapels.
The crypt beneath the Wawel Cathedral or St. Leonard's Crypt holds the tombs of Polish kings, national heroes, generals and revolutionaries, including rulers of the Polish-Lithuanian Commonwealth.
Upon the demise of the monarchy (and kingdom itself), the honour was extended to statesmen with Prince Józef Poniatowski (1817), Tadeusz Kościuszko (1818), poets Adam Mickiewicz (1890) and Juliusz Słowacki (1923), Józef Piłsudski (1935) and General Władysław Sikorski (1993) all securing themselves a place here. Most recently - in April of 2010 - the late President Lech Kaczyński and his wife Maria were controversially interred here after the tragedy in Smoleńsk.
Pope John Paul II also was considered being buried there also at one point in time, however that was not going to happen.
St. Leonard's Crypt under the Wawel Cathedral in Krakow, Poland, is a Romanesque crypt founded in the 11th century (around 1038–1039) by Casimir I the Restorer who made Krakow his royal residence as the capital.
At the end of the 11th century construction work began on the cathedral called 'Hermanowska'. It is probable that Wladyslaw I Herman was its benefactor. The cathedral was consecrated in 1142. More is known about this new structure because its image is featured on a chapter house seal from the 13th century and its present-day remnants are well preserved – including the lower part of the Silver Bell Tower.
The entire St. Leonard's Crypt is supported by eight columns. In 1118 bishop Maurus was buried there. The paten and the chalice were later exhumed from the tomb. This period also gave rise to the Rotunda by the Bastion of Ladislaus IV of Hungary from the 12th century, which could have been a baptistery for the royalty, the Church near the Dragon's Den, and the Rotunda by the Sandomierska Tower – probably from the second half of the 11th century.
The crypt holds the tombs of Polish kings and heroes such as:
- Michael I - King of the Polish-Lithuanian Commonwealth
- John III Sobieski - also King of the Polish-Lithuanian Commonwealth and Commander at the Battle of Vienna
- Marie Casimire - Queen of the Polish-Lithuanian Commonwealth and consort of John III Sobieski
- Jozef Poniatowski - Prince of Poland and Marshal of France
- Tadeusz Kosciuszko - Polish general, revolutionary and a Brigadier General in the American Revolutionary War
- Wladyslaw Sikorski - Prime Minister of the Polish Government in Exile and Commander-in-Chief of the Polish Armed Forces Pope John Paul II said his first Mass on the altar in St. Leonard's Crypt on November 2, 1946, one day after his priestly ordination.