Trinity Church (Holy Trinity Church) gives Irkutsk another layer of architectural and religious history. Even if you are not visiting for worship, the building is worth a pause for its setting, interior details, and the way it anchors the surrounding streets.
Visit respectfully and check whether services, closures, or restoration work affect access. A short stop is usually enough for casual visitors, but people interested in architecture or local history may want more time to look closely at chapels, stonework, memorials, and artwork.