Built to Robert Adam's design in 1796, the interior dates from the remodelling by the fourth Marquess of Bute in 1903, including the Adam-style ceiling in the first floor drawing room. For a long time the HQ of the National Trust for Scotland, No 5 is now the offices of the Edinburgh World Heritage Trust: www.ewht.org.uk Zoe Clark, Director of Edinburgh World Heritage says: "The Edinburgh World Heritage offices at 5 Charlotte Square will be open throughout the day, and we are inviting people to come along and discover why the city is a World Heritage Site. There will be an opportunity to look through our archive, and examine historical artefacts in detail to compare different styles of architecture. Children will be able to dress up as a resident of the Old Town in 1600 or a Georgian gentleman or lady from the New Town, and make their own mark on our giant World Heritage Site map. Visitors will also be able to explore Charlotte Square in the company of our costumed guides, and find out about Robert Adam's finest piece of design and the lifestyles of the original residents in 1800. Our aim is to encourage everyone to understand the world-class architecture around them and to value the things that make Edinburgh such a unique and admired place."