Old Oswestry is a large early Iron Age hill fort in the Welsh Marches near Oswestry in north west Shropshire, England. The earthworks, which remain one of the best preserved hill forts in the UK, have been described as "The Stonehenge of the Iron Age Period". After the hill fort was abandoned, it was incorporated into Wat's Dyke by the Mercians during the Early Medieval period.

The British Iron Age is a conventional name used in the archaeology of Great Britain, referring to the prehistoric and protohistoric phases of the Iron Age culture of the main island and the smaller islands, typically excluding prehistoric Ireland, which had an independent Iron Age culture of its own. The Iron Age is not an archaeological horizon of common artefacts but is rather a locally-diverse cultural phase.