While the climb up to Stirling Castle is not a major challenge in cycling terms, the esplanade at the summit offers spectacular views of the surrounding area, not to mention the historic castle itself.
Starting in Stirling town centre, you can climb up the cobbled King Street and past the Red Lion hotel from the pedestrian Murray Place or up Corn Exchange Road and past a statue of Robert The Bruce, the library and municipal buildings. From here continue up Spittal Street and past the Stirling Highland Hotel.
Past the hotel, and the Toolboth cultural centre, the road becomes Old John Street and the cobbles begin. This tough section lasts 2-300 metres, and is tough going until it levels out briefly, parallel to the Church of the Holy Rude and the ancient graveyards.
At this point you can turn back down Broad Street, and descend quickly through Baker Street, looping back around King Street to re-do the climb as many times as you fancy. In summer this area is choked with tourist traffic, so for race training the climb is best repeated early in the year. For those not of a masochistic tendency, follow the cobbled street all the way up to the Castle esplanade, past Hermanns and The Portcullis restaurants.
Gordon Goldie pointed out, on the Braveheart forum that the prologue of the ill fated PruTour in 1998 saw Boardman beating Ekimov up this climb.
Stirling Bike Club used to finish their midweek chaingangs up here, Mark Baugh adding that it was always the choice between the cobbles or riding in the narrow flat gutter trying not to bash your pedals on the curb, and then trying not to spew in front of the tourists in the castle car park.