In terms of walking Gorki I would say it's almost the same.Castle St may well be nearer [a bit] depending on where in that St. it drops you, but if you don't know Oxford all that well, it's more straightforward to get off at St Aldates [the top of St. Aldates] next to Carfax [where the streets go 4 ways.]High St to the right Queen St to the left and Cornmarket straight on.You would go straight down Cornmarket keeping on left hand side,until you come to cross the road by a large Debenhams.Keep going straight past Debenhams and you come to the Randolph hotel, turn left there and cross the road to the Asmolean museum on the other side.For anyone coming into the bus station who doesn't know Oxford; exit bus station into the market square, go to left hand side and into first little lane left[there are black bollardy things there.]keep left, past the small Burton Taylor theatre,and out into a broad street, turn right here, with The Oxford Playhouse on one side and the Ashmolean on the other.