St. Peter and Paul's Cathedral was designed by Carlo Rossi and completed in 1841. It is the Catholic Cathedral of Tallinn. During the period of Swedish rule (1561-1721) Catholicism was banned. When Sweden ceded Estonia to the Russian Empire at the end of the Great Northern War, the new authorities introduced religious freedom. In 1799, the Catholic parish grew and took over the use of the former refectory of St. Catherine's Monastery, which had remained closed since the ban. The refectory was used as a place of worship and is located on the site of the present church. In 1841, as the place of worship had become too small, a new church was designed by Carlo Rossi.
The Church of the Holy Spirit is the smallest medieval church in Tallinn. The first written documents mentioning the church date back to 1316. Between 1375 and 1380 several reconstructions and additions were made to the church. Originally, the church was a single-nave church, but as the congregation grew, a side nave was added. Major changes to the façade probably took place after the fire of 1433. Minor changes were also made in the 17th century when a new Baroque bell tower with two open balconies was built on top of the octagonal tower of the church, which resembles the exterior of the town hall in its appearance.
St. Olaf's Church was founded in the 12th century by the Scandinavians who occupied the city at that time and was named after King Olaf II of Norway. The building has been preserved as it was rebuilt in the early 15th and 16th centuries. The church also had to be partially rebuilt after fires in 1625 and 1820. The tower, which was destroyed in the fire of 1820, was restored in 1840, and at the same time, the neo-gothic interior of the church was completed.