The gothic triple-aisle building has had a complicated history. A smaller roman basilica, which had existed since before 1178, was gradually replaced by this church during the 14th and 15th centuries. The church was renovated in a Baroque style at the end of 17th century. Gothic renovation was done by Architect Josef Mocker in 1874-1879 and in 1913-1914.
The ancient church of St. Peter at Na Poříčí enhances Prague’s panorama with its four steeples. The two steeples in the forefront are 38m tall and their floor plan is 4.90m x 4.90m. They were constructed in a Romanesque style and refurbished in a Gothic style during 1483-1497. A baroque facade was given to the steeples after the conflagrations of 1653 and 1659, which affected the church as well. The next is a small ‘Sanctus’ steeple rising from the roof above the presbytery on the east side. None of the steeples have their bells today including the fourth steeple, which is two-storied and located above the north antechapel.
The detached belfry, 39.5m high, was built from sandstone blocks. The ground floor has a walk trough passage from the street. On the 3rd floor we can find 6 windows with pointed window arches. On the facia of the belfry there is an embedded broad stone with Latin lettering proclaiming: “The Commoners of St. Peter’s Church at Poříčí built this tower at their own expense and for their grateful descendants in 1598“. The top of this belfry is covered with a bulbous dome with lantern and with four clock faces. The belfry has 3 bells today. The largest, Peter, was cast in 1691 and re-cast in 1701. The second bell, called Pavel, (Paul) was created in 1724 and the last bell is a passing bell. The belfry is accessible through a small door on the south side. Solid newel stairs leads to the second floor, where all the bells are suspended. Steep wooden stairs then take us up to the tower where we can observe the bell cimbalom announcing even the quarter-hours.