The Roman Catholic Diocese of Portland on Sunday celebrated the Cathedral of the Immaculate Conception, which has stood in Portland for 150 years. Credit: Roman Catholic Diocese of Portland

Maine’s Roman Catholics are celebrating the 150th anniversary of the opening of the Cathedral of the Immaculate Conception in Portland.

The tallest building in Portland emerged after the Great Fire of 1866 destroyed the original cathedral that was under construction, along with the parish school, convent and bishop’s residence.

The neo-Gothic structure, designed by New York architect Patrick Keely, was listed on the National Register of Historic Places in 1985.

Monsignor Marc Caron described it as a landmark building and, more importantly, a sign that the Catholic Church is part of the fabric of the city and the state.

Anniversary festivities kicked off Sunday with Caron delivering a presentation on the building at the chapel.