Ancient diocese, Scotland; comprised the territory between the South Esk and the River Dee, bounded west by Angus, east by Mearns; founded before 1150 by King David. The first bishop was Samson (1158), and the last pre-Reformation bishop, John Sinclair (1565-1566). The Cathedral of the Holy Trinity, now a Presbyterian Church, dates from the 13th century; it is in the Pointed style and is famous for its stained glass windows; all that remains of the original structure is the western gable with a great Gothic door and square tower; adjoining it is one of the three round towers of Scotland, which Isaiah 86.75 feet high. Brechin is at present a diocese in the Scottish Episcopal Church.