The church was built in the grounds of a former Franciscan Friary that was dissolved in 1559. In the mid 1600s it was used as a barracks by Cromwell's troops and gunpowder was held in the tower. Perhaps inevitably, this exploded in the 18th century and destroyed the tower and damaged the two west bays.
Further disaster struck in January 1845 when a fire gutted part of the building, and fire damaged stones can still be seen. There is fine 19th century coloured glass by Ballantine and in 1990 a magnificent organ was built by Peter Collins Ltd, a well respected firm.
The National Covenant was signed here in 1638; this was a contract with God, signed by the Nobles, Ministers and thousands of ordinary Scots, who pledged themselves to defend Scotland's rights and the Presbyterian religion.
Greyfriars kirkyard, with views to Edinburgh Castle, is full of interest. It has exceptional examples of 17th century monuments, including the Martyrs' Monument and Covenanters' Prison.
It was also the setting for the story of Greyfriars' Bobby. When John Gray, a city night watchman, died in 1858 his loyal Skye terrier Bobby remained by his master's grave until his death 14 years later. The dog was not allowed to be buried in the churchyard but was laid to rest just outside, as close to his beloved master as possible. A red granite stone now stands in his memory with the words 'Let his loyalty and devotion be a lesson to us all.'