Hoddesdon is in the English county of Hertfordshire, situated in the Lea Valley. The town grew up as a coaching stop on the route between Cambridge and London. It is located 4 miles (6.4 km) southeast of Hertford, 5 miles (8.0 km) north of Waltham Cross and 11 miles (18 km) southwest of Bishop's Stortford. At its height during the 18th century, more than 35 coaches a day would pass through the town. It saw a boom in the mid 20th century as gravel was extracted from the area to be exhausted by the 1970s. The lakes and water pits left behind have been used for local leisure amenities. Today, Hoddesdon has a little light industry but is mainly a London commuter belt town. The town hosted the eighth Congres Internationaux d'Architecture Moderne in 1951. It is twinned with the Belgian city of Dinant.