The Dell is a house in Grays, Thurrock, Essex, built in concrete—one of the earliest houses in Britain to be built in this material. It was built on the instructions of Alfred Russel Wallace, who lived in Grays from 1872 until 1876.

Grays is the largest town in the borough and unitary authority area of Thurrock, in the ceremonial county of Essex, England. The town, which is both a former civil parish and one of Thurrock's traditional Church of England parishes, is located on the north bank of the River Thames.