Designed by Tylman Gamerski, the church consists of a large dome atop a basic Greek
cross design. The facade is baroque, although the interior is completely modern, because very few of the original furnishings of the church were preserved. Inside, the most valuable element of the original church's decoration are the preserved fragments of a brilliant tomb monument of Maria Karolina Sobieska de Bouillon carved by
Lorenzo Mattielli in white and black marble in 1746. The effigy of the founder in an oval frame was placed atop the
plinth with the
Janina coat of arms and a royal crown. The whole composition was completed with carved statues of the
personification of the
Polish–Lithuanian Commonwealth and a
putto, while the
arcade above was adorned with
skulls. The tombstone was reconstructed in 1961 by Antoni Szymanowski. ==
Charlotte, Duchess of Boullion's Monument==