In 1882-4, Frances Groome's Ordnance Gazetteer of Scotland described Innermessan like this:
Innermessan, a farm in Inch parish, Wigtownshire, on the E shore of Loch Ryan, 2½ miles NE of Stranraer. It contains the site of a mediæval town and an extant ancient moat. An ancient town is supposed to have preceded the mediæval one, and now is commonly identified with Rerigonium, a seat of the Caledonian tribe Novantæ, mentioned by Ptolemy in the 2d century A.D.(See Beregonium.) The mediæval town is said by Symson (1684) to have been ` of old the most considerable place in the Rhinns of Galloway, and the greatest town thereabout, till Stranraer was built;' but now it is represented by only a tiny hamlet. ...
Innermessan Castle, whose site is occupied by the neat farmhouse, was built by the first Sheriff Agnew of Lochnaw on grounds granted to him by royal charter of 1429, and continued to be inhabited till towards the close of the 17th century. Innermessan Moat, a circular, artificial mound, once surrounded by a fosse, measures 336 feet in circumference round the base, 78 in sloping ascent, and 60 in vertical elevation. Its flat summit, which commands a fine view, was bored in 1834, and then was found to contain a stratum of ashes, charred wood, and fragments of bone.Ord. Sur., sh. 3, 1856.
A Vision of Britain through Time includes a large library of local statistics for administrative units. For the best overall sense of how the area containing Innermessan has changed, please see our redistricted information for the modern district of Dumfries and Galloway. More detailed statistical data are available under Units and statistics, which includes both administrative units covering Innermessan and units named after it.
GB Historical GIS / University of Portsmouth, History of Innermessan, in Dumfries and Galloway and Wigtownshire | Map and description, A Vision of Britain through Time.
Date accessed: 13th December 2013
Click here for more detailed advice on finding places within A Vision of Britain through Time, and maybe some references to other places called "Innermessan".