St John's Cathedral, Catholic cathedral in Limerick, Ireland

St John's Cathedral is a Roman Catholic cathedral on Cathedral Place in Limerick, designed by Philip Charles Hardwick in a severe Gothic Revival style. Its walls are faced with local limestone, and the exterior has minimal decoration and small windows, with just one statue on the façade. The tower and spire, adapted by M.A. Hennessy, rise 81 m (266 ft).

Designed by English architect Philip Charles Hardwick, the cathedral replaced a chapel founded in 1753; its foundation stone was laid on 1 May 1856 and the first Mass was celebrated on 7 March 1859. Thomas Byrne built the tower and spire from 1879, work delayed by storm damage in September 1882, and Cardinal Logue consecrated the completed interior on 21 June 1894.

The cathedral's name honours St John the Baptist, and its Irish title is Ardeaglais Eoin. Much of the original 19th-century furnishing survives inside: pews, confessionals, memorials and floor tiles. The bishop's throne, or cathedra, was made in Munich in 1894 and has since been removed.

Visitors can attend regular services and observe the interior at appropriate times, which vary based on religious ceremonies and gatherings. It helps to check ahead about opening times and to be respectful of worship activities happening throughout the day.

The altar is carved from Limerick marble with a relief of the Sacrifice of Abraham, a detail easy to miss. The building was long said to have Ireland's tallest spire at 94 m (308 ft); modern measurement puts it at 81 m (266 ft), below St Colman's Cathedral in Cobh.