The full extent of a hillfort likened to an Iron Age "Millennium Stadium" has been uncovered by investigators.

Gaer Fawr hillfort at Guilsfield, near Welshpool, Powys, is effectively hidden by woodland, making it impossible to appreciate the scale of it.

Detailed survey by the Royal Commission on the Ancient and Historical Monuments of Wales produced a computer model of the site which dates from around 800BC.

The fort features in the BBC Wales programme Hidden Histories on Tuesday.