Inchtuthil is the site of a Roman legionary fortress situated on a natural platform overlooking the north bank of the River Tay southwest of Blairgowrie, Perth and Kinross, Scotland (Roman Caledonia).
It was built in AD 82 or 83 as the advance headquarters for the forces of governor Gnaeus Julius Agricola in his campaign against the Caledonian tribes. Positioned at the head of one of the main routes in and out of the Scottish Highlands, it was occupied by Legion XX Valeria Victrix and covered a total area of 21.5 hectares (53 acres). Construction of the large fortress would have taken two or three seasons and a temporary camp was built nearby to house and protect the soldiers over the winter. Additional, smaller forts were built further north and south at the mouth of each nearby glen forming what are now referred to as the Glenblocker forts.
Woolliscroft and Hoffmann argued that the Glenblocker forts, as well as others in Strathmore, such as Cardean and Stracathro, formed a uniform system composed of several elements, the forts and watchtowers on the Roman road of the Gask Ridge, the Glenblockers and the Strathmore forts. Inchtuthil as the largest military base would have functioned as the lynch-pin and the only site large enough to launch an invasion into the Highlands and beyond.