Radlett is a town in Hertfordshire, England, between St Albans and Elstree on Watling Street, with a population of 8,042. It is in the council district of Hertsmere in the south of the county, and is covered by two wards; Aldenham East and Aldenham West. It is located inside the M25 motorway.

Radlett lies in the valley of Tykes Water, a stream that runs north from Aldenham Reservoir to the River Colne. Now entirely surrounded by the Metropolitan Green Belt, it is subject to significant 'infill' development and there is pressure to relax the Green Belt restrictions.

Radlett is located 14 miles (22.5 km) north west of the centre of London. It is one of the wealthiest places in Britain and the second most expensive town to buy a house outside London. The town contains many substantial detached houses with large gardens. In the older centre there are also a few streets with Victorian semi detached and terraced houses.

Watling Street, which is the main road through Radlett, has a wide variety of local shops and restaurants, as well as some national chain stores, a Post Office inside the local Budgens supermarket, and the Radlett Centre[5] with a 300-seat auditorium for various performances. Attached to the Radlett Centre is the local Public Library.

There are two public houses in Radlett, "The Office" and "The Red Lion".

Radlett is situated on the ancient Watling Street, one of the oldest trackways in Britain. Various archaeological finds of Mesolithic and Neolithic flints provide evidence that the Radlett area was inhabited in the Stone Age; the land was densely wooded and remained so until the Middle Ages. The Catuvellauni tribe settled in parts of Hertfordshire, near St Albans and Wheathamstead in about 80BC, although no trace of settlement has been found in or near Radlett itself. The name Radlett appears to come from the Old-English rad-gelaete meaning a junction of the roads and it is likely that the settlement grew at the point where the ancient route from Aldenham to Shenley crosses Watling Street.

During the Roman occupation of Verulamium, the area from Radlett to Brockley Hill was home to a number of major potteries, which supplied not only the Roman capital but other parts of the province. One of these potteries is known to have existed on Loom Lane. Roman-era clay pits are still in evidence at the southern end of the village, in the area around Cobden hill and Tabard RFC. In addition, there is evidence of a Roman villa with a bath building, barn and tile kiln dating from 2nd to 4th century AD, in the area of Netherwylde Farm.