[1] Constructed from 1801–05 as part of Union Street under plans suggested by Charles Abercrombie, it was intended to provide an impressive approach into the city from the south (and west); previously the route had been somewhat circuitous.

The bridge was widened in 1908, in a scheme of William Diack, with Benjamin Baker as consultant, shortly before the latter's death.

Steel side spans which carry today's pavements were introduced, as were the famous "Kelly's cats", black cast metal leopards which sit along the balustrade.

[3] The southern side of the bridge, including the cats, was hidden, and the view lost, when shops were constructed along it in the 1960s.

[5] A permanent barrier was completed as part of works to redevelop the adjacent Union Terrace Gardens.