St. Giles Cathedral
Updated: May 17, 2020
St. Giles Cathedral is an impressive Gothic cathedral was built as a Catholic cathedral in the 14th to 16th century, on the ruins of a former temple from the 12th century. After the Scottish Reformation (1560), it became Presbyterian.
The entry is free (You'll have to pay for taking pictures), and it's in the middle of the Royal Mile, so I think it worth getting in for a few minutes.