The A404 is a road in the United Kingdom that starts at Paddington in London and terminates near Maidenhead in Berkshire. It is 44.6 miles (71.8 km) long.

Maidenhead is a market town in the Royal Borough of Windsor and Maidenhead in the county of Berkshire, England, on the southwestern bank of the River Thames. In the 2021 Census, it had an estimated population of 70,374 and forms part of the border with southern Buckinghamshire. The town is situated 27 miles (43 km) west of Charing Cross, London and 13 miles (21 km) east-northeast of the county town of Reading. The town differs from the Parliamentary constituency of Maidenhead, which includes a number of outer suburbs and villages, including villages which form part of the Borough of Wokingham such as Twyford, Charvil, Remenham, Ruscombe and Wargrave.