Chesham is a market town and civil parish in Buckinghamshire, England, United Kingdom, 11 miles (18 km) south-east of the county town of Aylesbury, about 26 miles (42 km) north-west of central London, and part of the London commuter belt. It is in the Chess Valley, surrounded by farmland. The earliest records of Chesham as a settlement are from the second half of the 10th century, although there is archaeological evidence of people in this area from around 8000 BC. Henry III granted a royal charter for a weekly market in 1257.

The River Chess is a chalk stream that rises near Chesham in the Chiltern Hills, and flows for 11 miles (18 km) through Buckinghamshire and Hertfordshire to its confluence with the River Colne in Rickmansworth. The Chess, along with the Colne and Gade, gives rise to the name of the district of Three Rivers.