The Church of St Nicholas, the most famous Baroque church in Prague, stands along with the former Jesuit college in the centre of the Lesser Town Square. A Gothic parish church consecrated by Prague Bishop Tobiáš in 1283 stood at the site until 1743; nearby was the Romanesque Rotunda of St Wenceslas, which had been built in memory of the miracle that occurred during the transfer of Wenceslas’ body from Stará Boleslav to Prague Castle, as mentioned in medieval legends.
Today’s Church of St Nicholas is one of the most valuable Baroque buildings north of the Alps. Construction lasted approximately one hundred years, and three generations of great Baroque architects – father, son and son-in-law – worked on the church: Kryštof Dientzenhofer, Kilián Ignác Dientzenhofer and Anselmo Lurago.
The Jesuit Thomas Schwarz built the small and main organs as well as many others in Bohemia. Built in 1745-47, the main organ has over 4,000 pipes up to six metres in length. W. A. Mozart played this organ during his stay in Prague as a guest of the Dušeks.
The Church of St Nicholas is a superb example of High Baroque architecture, a building that astonishes visitors with its size and monumental interior. As the most prominent and distinctive landmark in the Lesser Town, no panoramic view of the city would be complete without its silhouette below Prague Castle.
Construction lasted approximately one hundred years, and three generations of great Baroque architects – father, son and son-in-law – worked on the church: Kryštof Dientzenhofer, Kilián Ignác Dientzenhofer and Anselmo Lurago. Although the church underwent certain developmental transformations, the resulting building is an architectural gem.
The diameter of the dome is an impressive 20 m; the height inside the church to the top of the lantern is almost 57 m, making it the tallest interior in Prague. Highlighting the unique aesthetic impact of the building is the direct connection of the adjacent slender belfry and the church’s massive dome. Both are 79 m tall. The belfry, which, unlike the church, belongs to the city, was completed in diminutive Rococo forms in 1751-56 by Anselmo Lurago following Dientzenhofer’s death.
A vast crypt with barrel vaults that ingeniously utilised the sloping terrain was built beneath the entire ground plan of the church. Completed in 1710, the facade of the church is composed of waves of alternating concave and convex forms, the dynamic effect of which is intensified by a trio of large gables towering over the elevated central part with a larger than life-sized statue of St Nicholas from the workshop of sculptor Jan Bedřich Kohl, the inscription IHS and a crucifix. The actual facade, decorated with the crest of the church’s greatest patron, Franz von Kolowrat-Liebsteinsky and stone sculptures of the Western Fathers of the Church, is the purest example of the Roman Baroque in Prague. Semi-circular staircases lead to a trio of grand entrances. Despite the differences in the designs and styles of the father and son architects, the Dientzenhofers combined a strong sensitivity for the plasticity of forms. Despite their formal differences, all columns, capitals, consoles, portals and window chambranles are skilfully subordinated to a uniform harmony.
(source and read more: http://www.stnicholas.cz/en/)