The Medway Megaliths, sometimes termed the Kentish Megaliths, are a group of Early Neolithic chambered long barrows and other megalithic monuments located in the lower valley of the River Medway in Kent, South-East England. Constructed from local sarsen stone and soil between the 4th and 3rd millennia BCE, they represent the only known prehistoric megalithic group in eastern England and the most south-easterly group in Britain.

The River Medway is a river in South East England. It rises in the High Weald, West Sussex and flows through Tonbridge, Maidstone and the Medway conurbation in Kent, before emptying into the Thames Estuary near Sheerness, a total distance of 70 miles (113 km). About 13 miles (21 km) of the river lies in East Sussex, with the remainder being in Kent.