The North Riding extends from the fells on the Westmorland border to the highest cliffs in England, facing the North Sea. In an area of scattered settlements, Richmond is one of the best market towns in England, as Whitby is one of the best fishing towns. There are remains of twenty medieval monastic houses, including the unusually complete and beautiful work at Rievaulx, complemented by fine 18th century landscaping. The North Riding also saw Vanbrugh's astonishing first essay into architecture at Castle Howard, and there are many fine classical houses in a distinctively northern style. Industry has made its mark along the estuary of the Tees, where the Middlesborough transporter bridge is a unique working survival of early 20th century engineering.