Church of St. Nicholas Within, Medieval church building in central Dublin, Ireland.

The Church of St. Nicholas Within is located at the corner of Nicholas Street and Christchurch Place, displaying stone walls and architectural details from multiple periods. Its visible remains sit next to Peace Park, which now defines the area with green space.

Bishop Donat founded this religious site in the 11th century and dedicated it to Saint Nicholas of Myra. A major reconstruction took place in 1707 that modernized the building.

The parish was divided into two sections: one inside the city walls and one outside, reflecting how Dublin's religious life was organized in medieval times. This split shaped how people attended church and which community they belonged to based on where they lived.

Only the entrance portal survives, set beside the Peace Park off Christchurch Place; it was dismantled and rebuilt about 10–15 metres back from its original corner position during road widening in 1911. Look for it at the junction with Nicholas Street, a short walk from Christchurch Cathedral and Dublin Castle.

The cemetery once held the remains of Nathaniel Catelyn, a Speaker of the Irish Parliament, before parts of the ground were repurposed for building the Tholsel. This change shows how Dublin's growth altered the ancient burial ground.