One of the most important events in St. Brigids life was the foundation of Kildare Cathedral. The cathedral started out as a small kill or church, built near a great oak tree. It was from the church and tree that the surrounding area took its name Cill-Dara "church of the oak". This later extended to the town, county and finally diocese. And so, in 470 A.D., St. Brigids monastery was founded and her growing number of converts spread throughout the land. Brigid decided that she needed a bishop and so the person she chose was St. Conleth (also known as Hugh the Wise) - the first bishop of Kildare.
The cathedral and its adjacent round tower reflect the style of eighth century Christian settlements. Outside the cathedral are the remains of the ancient High Cross of Kildare. During renovations carried out on the cathedral and its grounds, an ancient granite font was discovered and this was placed in the nave. In 1871 restoration work was begun as the cathedral had fallen into disrepair. Work commenced to repair the stonework, roof and floor of the nave and trancepts. This was completed in 1896. More repairs were carried out to the exterior of the building in the 1980s.
The cathedral contains many treasures, including an altar frontal designed by English artist, John Ninian Comper. The design of the frontal uses the symbolism of the story of the Patron Saint. In 1991, as part of the celebrations of the centenary of the Co. Kildare Archeological Society, some of the Cathedral treasures including the plate, were displayed.
Today work is still being carried out on the cathedral to ensure the conservation of one of Irelands most historical ecclesiastical buildings.