The Trinity Church is one of the oldest surviving churches in Irkutsk. It was built in the second half of the 18th century and consecrated in 1778. It is an example of what is known as Siberian baroque. During the Soviet era the church was used as a planetarium. Just next to this church is the smaller and simpler St Gregory of Neocaesarea's Church which dates from 1805 and was built in the classical style.