St Mary's Church, Navan, Catholic church in Navan, Ireland

St Mary's Church stands on Trimgate Street with substantial stone walls and architectural features typical of 1830s religious buildings in Ireland. The structure contains a spacious nave with elaborate interior appointments and occupies a prominent position on the street.

The church opened in 1839 following Catholic Emancipation and replaced a medieval Augustinian abbey that King Henry VIII dissolved during his conflict with Rome. It was built as a response to new religious freedom that allowed Catholics to finally construct large churches in Ireland.

The church is named after a medieval Augustinian abbey on the parish outskirts, suppressed on the orders of King Henry VIII. Behind the reredos hangs a life-size wooden crucifix by Edward Smyth, the County Meath sculptor known for the riverine heads on Dublin's Custom House. The Anglican St Mary's stands a short distance away.

Access is from Trimgate Street and the building is open to visitors during prayer times. Those wishing to view the architecture and interior fittings in quiet should visit between scheduled services.

Local lore holds that Fr. Eugene O'Reilly, who called the 1834 meeting that launched the building, had a Paris opera house in mind and copied its dimensions; the claim was never proven, though the theatrical design is often cited as support. O'Reilly had studied in Lille, where a theatre opened in 1785 and burned down in 1903.