Most people only admire this Baroque pile from the outside which is a shame, the interiors are even lovelier. Began in 1673, it would be nearly another 80 years until the Jesuits completed it. Inside, take note of the copper statue of St. Nicholas above the gold coated altar; the two statues below him are of St. Ignatius Loyola and St. Francis Xavier. The ceiling fresco depicts the apotheosis of St. Nicholas. Also of interest is the organ, which has 2500 pipes and 44 registers, and it was these very ivories that Mozart tinkled on his visit to Prague. Organ concerts are held regularly.