Christ Church Cathedral, more formally The Cathedral of the Holy Trinity, is the cathedral of the United Dioceses of Dublin and Glendalough and the cathedral of the ecclesiastical province of the United Provinces of Dublin and Cashel in the (Anglican) Church of Ireland. It is situated in Dublin, Ireland, and is the elder of the capital city's two medieval cathedrals, the other being St Patrick's Cathedral.

The cathedral was founded in the early 11th century under the Viking king Sitric Silkenbeard. It was rebuilt in stone in the late 12th century under the Norman potentate Strongbow, and considerably enlarged in the early 13th century, using Somerset stones and craftsmen. A partial collapse in the 16th century left it in poor shape and the building was extensively renovated and rebuilt in the late 19th century, giving it the form it has today, including the tower, flying buttresses, and distinctive covered footbridge.