Everyone should experience a trip over Thomas Telford and William Jessop's awe-inspiring aqueduct, by boat or on foot. Granted World Heritage Status in June 2009, this maginificent example of 19th century engineering ingenuity carries the Llangollen Canal over the beautiful River Dee valley. The structure is 1,000 feet long and 125 feet high. Such distances had never before been conquered, until Telford's audacious decision to build it by laying an iron water-carrying trough on stone piers. To this day, the joints are effectively sealed using a mixture of flannel and lead dipped in liquid sugar.