St Giles’ was the most important church in the burgh of Edinburgh (although it was not a cathedral until the 1630s). In 1544 St Giles’ was still a Catholic Church. It was lavishly decorated with statues and stained glass, and housed the altars of the local craft guilds. The feast day of St Giles (on 1st September) was marked by a religious procession along the Royal Mile. In 1558 Protestant Reformers disrupted the religious festivities, throwing a statue of St Giles to the ground, and smashing it upon the paving stones. Two years later Scotland officially rejected Catholicism, and St Giles’ became a Protestant place of worship.
The Canmore entry for St Giles Kirk is here.