Swansea's Guildhall will be opened to the public as part of the programme
Wales is set to celebrate its rich architectural heritage by opening the doors of some of its best buildings to the public.
The Civic Trust for Wales is offering free entry to heritage sites across the country over the next three weekends as part of its Open Doors Days programme.
It offers free access to properties often closed to the public with more than 200 sites taking part.
Trails linking sites have been set up in Swansea, Monmouth and Denbigh.
In Swansea, people will be able to visit Oystermouth Castle and the city's historic Guildhall, while in Cardiff guided tours of BBC Wales and the Media Wales newsroom, where the Western Mail newspaper is put together, will take place.
In Monmouth, the town's historic Cornwall House and Savoy Theatre will open their doors while in Pembrokeshire people will be given the chance to visit the World War II Carew Cheriton airfield control tower.
More than 300 events will take place over the next few weekends with the programme coming to an end on the weekend of 20 and 21 September.
A host of volunteers including civic societies, churches, local museums and building and site owners have organised the events which will provide a behind-the-scenes look at each venue aided by associated exhibitions, talks and, in some cases, concerts.
In 2007, more than 40,000 people took advantage of the scheme in Wales and organisers believe this year's programme will be bigger than ever before.
Dr Matthew Griffiths, of the Civic Trust for Wales, said: "This is a very special chance to learn about our hidden heritage or to find out something new about somewhere that may be familiar.
"Wales has a particularly rich heritage and the event offers everyone a chance to learn about more about its historic buildings and the importance of conserving our historic environment as a legacy for future generations."
The public will be able to gain instant access to historic homes, castles, industrial sites, public buildings, museums and gardens.
But visits to some sites will need to be booked in advance as smaller historic buildings and some private homes can only cope with a few visitors at a time.
The Open Doors Days scheme is part of the successful European Heritage Days which each celebrates Europe's common cultural heritage in more than 40 states and brings in 20m visitors each September.