One of the features of this bridge that fascinates me is that the vertical loading stresses are almost constant. When a boat passes over, it displaces it's own weight in water, unlike on a viaduct, where every vehicle passing over imposes a separate strain and weight on the structure.
Telford is one of my heroes. Rolt's superb biography (Sutton, ISBN 978-0-7509-4576-9) gives a touching and exhaustive account of his life, while admitting that the real man behind the engineering triumphs still eluded him. Why look any further than this bridge for confirmation of genius?
Wikipedia site for the Bridge for the facts and figures.
Thomas Telford, Dumfries and Galloway for a nice potted history of the man.