It is thought that a small (probably wooden) church stood here already in Gediminas' times. In ca. 1408 Vytautas built the church of the Holy Spirit that was later expanded. In 1501 Alexander Jagiellon gave it to the Dominican Monastery, the oldest in Lithuania. An entry under the altar leads to the large vaults, which are labyrinthine, with many rooms and crypts. The dungeons house remains of hundreds of Vilnius residents, some of them naturally mummified, and are surrounded by urban legends.

Napoleon's soldiers are known to dismantle coffins for firewood here,  urban legends claim that these remains are of French soldiers from the 1812 French invasion of Russia or of victims of the Inquisition or plague. More romantic are claims that these dungeons were once part of a larger tunnel network that allowed legendary lovers Barbara Radziwiłł and Sigismund II Augustus to meet in secret.

Please note: not available to public as of July 2019.

Read more: https://en.wikipedia.org/wiki/Dominican_Church_of_the_Holy_Spirit