Cadw, the Welsh Assembly Government's historic environment service, has started preservation work at the site Owain Glyndwr is said to have declared himself Prince of Wales.

The man-made motte at Glyndyfrdwy near Corwen, Denbighshire, was one of Glyndwr's main residences and Cadw has raised concerns that it is danger of collapse. Work to preserve the site will be funded through the Welsh Assembly Government's Strategic Capital Investment Fund. Dawnus Construction is working with consultants Opus on the scheme.

It will form part of a wider £2m commitment to restoring some of Wales' historic medieval landmarks. The proclamation of Glyndwr as Prince of Wales in 1400 marked the start of a war of independence for Wales. Welsh heritage minister Alun Ffred Jones said: "The work to stabilise this iconic monument and improve access to the site will ensure that it can be enjoyed by future generations.

"It's appropriate that the beginning of this work should coincide with the [610th] anniversary of this important event in Welsh history."