 The quarter's eponymous road, Castlegate, was originally part of the main thoroughfare from the city centre to the north of the city, linking Park Square to The Wicker; however, the completion of the Sheffield Northern Relief Road dual-carriageway in 2007 redirected traffic away from the Castlegate area, and the road was downgraded.Castlegate was built along the southern bank of the River Don along the north side of what was once Sheffield Castle, and was originally the location of several slaughterhouses.It has also subsequently served as a back entrance to the Alexandra Opera House and then the Castle Market, which was constructed in the 1960s to provide permanent accommodation to tradesmen.