The occurrence of lady chapels varies by location and exist in most of the French cathedrals and churches where they form part of the chevet. In Belgium they were not introduced before the 14th century; in some cases they are of the same size as the other chapels of the chevet, but in others (probably rebuilt at a later period) they became much more important features. Some of the best examples can be found in churches of the Renaissance period in Italy and Spain.
It was in lady chapels, towards the close of the Middle Ages, that innovations in church music were allowed, only the strict chant being heard in the choir.
In the 12th-century legends surrounding KingLucius of Britain, the apostlesFagan and Duvian were said to have erected the Lady Chapel at Glastonbury as the oldest church in Britain; the accounts are now held to have been pious forgeries. The earliest English lady chapel of certain historicity was that in the Saxon cathedral of Canterbury; this was transferred in the rebuilding by Archbishop Lanfranc to the west end of the nave, and again shifted in 1450 to the chapel on the east side of the north transept. The lady chapel of Ely Cathedral is a distinct building attached to the north transept which was built before 1016. At Rochester the current lady chapel is west of the south transept (which was the original lady chapel, and to which the current chapel was an extension).
Probably the largest lady chapel was built by Henry III in 1220 in Westminster Abbey. This chapel was 30 feet (9.1 m) wide, much in excess of any foreign example, and extended to the end of the site now occupied by Henry VII's Lady Chapel. Also in 1220, the office of Warden of the Lady Chapel was established, with the responsibility for the Lady altar, and its sacred vessels, candles and other accoutrements.