St. Patrick's cathedral

Ireland's largest church, St Patrick's Cathedral, stands on what is probably the oldest Christian site in Ireland. A wooden church was built here in the fifth century after Ireland's patron saint, St Patrick, baptised his first Christian converts at a well on the site.
Although unusual to find two Protestant cathedrals within a few hundred yards of each other, St Patrick's was considered to be outside the city, while Christ Church was within the city walls. The present church at St Patrick's is thought to date from the end of the 12th century.
As well as an abundance of religious and military artefacts, St Patrick's boasts Ireland's largest organ, and statues of Jonathan Swift, dean of the cathedral between 1713-1745, and Douglas Hyde, Ireland's first president, among others.
One of the more interesting features is a hole, dating from 1492, which is cut into the door of the Chapter House. During a quarrel between two Norman earls, one of them, Lord Ormonde, took refuge in the Chapter House. When the dispute was resolved, the other earl, Lord Kildare, cut a hole in the door so he could safely shake hands with his former foe. Hence the expression 'to chance your arm'.
The cathedral has a long and illustrious musical tradition - St Patrick's Choir School was founded here in 1432 - and sung services, open to all, are held most days.