During the Roman occupation of Britain, when a new Roman garrison was built then often just outside the garrison a Vicus would grow up.
A Vicus was a collection of houses/businesses who hoped to offer services to the soldiers in the Garrison. These would be food, drink, clothing etc as well as metal or glass working.
One assumes there would be a main road leading into or out of the garrison, and I suppose the prime spot for one of these "shops" would have been alongside the main road so any Roman soldier entering or leaving the garrison would see the things available for sale.
I guess this may have been the first "high street", though I am not sure what businesses would have been available - hairdressers maybe, or shoe menders that sort of thing.
I guess a lot of these Vicus would have collapsed when the garrison closed or moved, but I am sure many grew up to become vilages or towns in their own right, and the collection of businesses would form the basis of the high street.
http://en.wikipedia.org/wiki/Vicus