As the name implies, it is dedicated to St. Giles, who was the patron saint of cripples and lepers and a very popular saint in the Middle Ages. The oldest parts of the building are four massive central pillars, often said to date from 1124, although there is very little evidence to this effect. In 1385 the building suffered a fire and was rebuilt in the subsequent years. Much of the current interior dates from this period. Over the years many chapels, referred to as 'aisles', were added, greatly enlarging the church and leaving it rather irregular in plan. In 1466 St Giles was established as a collegiate church. In response to this raising of status, the lantern tower was added around 1490, and the chancel ceiling raised, vaulted and a clear storey installed. By the middle of the 16th century (before the Reformation) there were about fifty altars in the church.