In 1770 the harbour was remodelled by John Smeaton, who introduced water tunnels to tackle the perennial problems caused by the vast quantities of silt washed down the Tay which formed sandbanks in the harbour and blocking it.
In 1815 a Habour Act was passed which moved control of the harbour from the Town Council to a Board of Harbour Commissioners. Under their guidance the harbour was greatly expanded from the 1820s with the addition of King William IV Dock, Earl Grey Dock, Victoria Dock and Camperdown Dock.
In 1844 a triumphal arch made of timber was erected at the entrance of the harbour to mark the arrival, by sea, of Queen Victoria on her way to her first holiday in Aberdeenshire.
In 1849 a competition was held to design a replacement permanent structure. The competition was won by a design submitted by James Thomas Rochead. The resulting Royal Arch quickly became one of Dundee's most iconic symbols.
King William IV Dock and the Early Grey Dock were filled in in the 1960s during the construction of the Tay Road Bridge and its approach roads and the Royal Arch was demolished at the same time
Sources of Information
-  Wikipedia