Kilmore Diocese was established a church at Kilmore near where Cavan town is now situated.Andrew McBrady, who was bishop of the diocese from 1445 to 1455, rebuilt the ancient church of St. Felim. Pope Nicholas V allowed him to make this his cathedral and it became known as An Chill Mhór, and this cathedral gave its name to the diocese, a name which has remained ever since. The Cathedral passed into the hands of the Church of Ireland at the Reformation.