The Cathedral of the Immaculate Conception is a historic cathedral at 307 Congress Street in Portland, Maine that serves as seat of the Diocese of Portland. The pastor is Bishop Robert Deeley, and the rector is Father Seamus Griesbach. The church, an imposing Gothic Revival structure built in 1866–69, was listed on the National Register of Historic Places in 1985. It is the tallest building in Portland and the third tallest in Maine.