When was Westminster Abbey built?

The first church: 960 to 1065

The story starts with monks around 960. The Abbey's history page says a small Benedictine monastery was founded on the site under the patronage of King Edgar and St Dunstan around that year. Edward the Confessor rebuilt it on a much larger scale next to his palace; Wikipedia dates the start of his work to between 1042 and 1052. His new church was consecrated on 28 December 1065. Edward was too ill to attend and died days later, on 5 January 1066, and he was buried in the church he had built. The first documented coronation there, William the Conqueror's, followed later in 1066.

The present church from 1245

Henry III began the church you see today on 6 July 1245, replacing Edward's building in the Gothic style. He built it as a shrine to venerate Edward the Confessor. The first stage covered the whole east end, the transepts and the easternmost bay of the nave, and the new church was consecrated on 13 October 1269, the day Edward's remains were moved to the shrine behind the high altar. Henry died in 1272, and was buried in the Abbey, before the nave could be completed, so, as the Abbey's history page puts it, the older structure stood attached to the new church for many years.

The nave, the Lady Chapel and the west towers

The rest took centuries. From 1376, Abbot Nicholas Litlyngton and King Richard II paid to finish the nave, and the master mason Henry Yevele followed the 13th-century design closely. Wikipedia dates the end of the nave, with the west window, to 1495. Henry VII began his Lady Chapel at the east end in 1503; the main structure stood by 1509 and the Abbey says it was consecrated on 19 February 1516. The last piece was the pair of western towers, completed in 1745 to a design by Nicholas Hawksmoor, with John James.

Who designed and built each part

No single architect designed the Abbey, and each phase had its master mason. Henry III's church was begun under Henry of Reynes, followed by John of Gloucester from around 1253 and Robert of Beverley from around 1260. Henry Yevele carried on the nave from the 1370s. Henry VII's chapel, begun in 1503, is in the late Perpendicular Gothic style. The west towers were completed in 1745 to Nicholas Hawksmoor's design, and Wikipedia credits them to Hawksmoor and John James.

• 1245 onward — Henry of Reynes, then John of Gloucester and Robert of Beverley: the Gothic east end and transepts.
• From 1376 — Henry Yevele: the nave, completed by 1495.
• 1503 to 1516 — Henry VII's Lady Chapel.
• To 1745 — Nicholas Hawksmoor, with John James: the west towers.

How long it all took and how old it is

From Henry III's start in 1245 to the towers in 1745 is 500 years. The site has been a church for more than 1,060 years if you count from the monastery of around 960, and the present church is about 780 years old. It was damaged on the night of 10 to 11 May 1941, when incendiary bombs hit the precincts and roof and the lantern over the crossing collapsed; no one was killed and services went on. You can see the medieval building, its tombs and its later additions on a single visit; book a ticket or a guided tour to see them with commentary.