The Union Chain Bridge spans the River Tweed between Horncliffe, Northumberland, England and Fishwick, Borders, Scotland. It was designed by Captain (later Sir) Samuel Brown RN, who held patents for the design of the chains, although Brown altered the tower and abutments on the suggestion of John Rennie. When it opened in 1820 it was the longest wrought iron suspension bridge in the world with a span of 137 metres (449 ft), and the first vehicular bridge of its type in the United Kingdom. It cost 7,700 to construct and pre-dates the Clifton Suspension Bridge and the Menai Bridge, which are of similar design . Today it continues to carry traffic, and visitors can enjoy pleasant walks along the river bank.Just up the hill from the Union Chain Bridge on the English side is the Chain Bridge Honey Farm, where there is situated a permanent exhibition on chain suspension bridges. Downstream on the Scottish side is Paxton House, where visitors can see Alexander Naysmith's depiction of Union Chain Bridge, painted before its actual completion.The OS reference for the Union Chain Bridge is NT933510.