Major conservation work is being undertaken on one of the historical entrances into the old walled town of Caernarfon in Gwynedd.
Porth Mawr, also known as East Gate or Exchequer Gate, was the main entrance into the town in the 13th Century.
Caernarfon Castle is also undergoing works to improve access for disabled people.
Cadw, which looks after Welsh historical monuments, said it would eventually be opened to the public.
Heritage Minister Rhodri Glyn Thomas said the work being undertaken at Caernarfon highlighted the challenges of improving access while preserving architectural and archaeological sites.
"Cadw is using its skill and imagination and those of specialist designers to develop solutions that are elegant as well as practical," he said.
Work on the Porth Mawr would mean access to areas of the town wall not now available to the public, said Mr Thomas.
"Cadw is working with local partners, including the county and town councils, to find a suitable and practical reuse for this important building so that it can again become a major feature of the town," he added.
The high town walls were built by the English to keep the Welsh out.
Traders paid tax on goods brought for sale at a small tower before crossing the drawbridge.
Rooms above the gate housed the royal exchequer, as Caernarfon was the administrative centre for Anglesey and the areas then known as Caernarvon and Meirioneth.
Both towers have been used for a variety of purposes over the years.
The renovation work will include restoring the old clock housed in the gate walls, and the curfew bell which rang when the gates were about to be closed.