Truro is a small cathedral city population 22,000 in the Duchy of Cornwall, of which it is the administrative capital.
The Cornish will insist this is a city. Anyone from outside of Cornwall will have visions of a built-up centre with a large conurbation and a good public transport system: don't. Truro is a practical city once you're in, and residents of other Cornish Towns will often visit to shop with more variety. But, unless you're staying within walking distance of the centre, expect to either drive in or have to plan a journey. There is a very small 'inner-city' area surrounding the centre. Even the most immediate 'suburbs' are small villages that have nothing but a few miles of field and a winding road separating them from the centre.