The Minor Basilica of the Immaculate Conception, The Cathedral, is located in the centre of three well known streets, Peynier Street, Micoud Street and Laborie Street, and is opposite the Derek Walcott Square in Castries, Saint Lucia. It is part of the Roman Catholic Archdiocese of Castries, the current Archbishop being Archbishop Gabriel Malzaire. The cathedral is named after Mary, mother of Jesus, under her title, Our Lady of the Immaculate Conception.

The form "Cathedral", as it is commonly known, is the largest church in the Caribbean, measuring 200 ft long (61 m) by 100 ft wide (30 m) and was given the honorary status of a Minor Basilica on 11 May 1999 as part of the centenary celebrations.

The interior is decorated by a mural by St. Lucian artist Dunstan St. Omer.