Designed by Jan Krzysztof Glaubitz in the 18C, the early Baroque Church of the Holy Spirit is the country's foremost place of Orthodox worship. You enter through the monastery's neo-Byzantine portal; inside, a peppermint-green Baroque altar (18C) serving as an iconostasis stands out against the vaults and the pink, blue and white columns. The crypt holds the bodies of three saints (John, Anthony, and Eustathios), 14C martyrs.