From the World Heritage inscription:
Edinburgh has been the Scottish capital since the 15th century. It has two distinct areas: the Old Town, dominated by a medieval fortress; and the neoclassical New Town, whose development from the 18th century onwards had a far-reaching influence on European urban planning. The harmonious juxtaposition of these two contrasting historic areas, each with many important buildings, is what gives the city its unique character.
The remarkable juxtaposition of two clearly articulated urban planning phenomena. The contrast between the organic medieval Old Town and the planned Georgian New Town provides a clarity of urban structure unrivalled in Europe. The juxtaposition of these two distinctive townscapes, each of exceptional historic and architectural interest, which are linked across the landscape divide, the “great area” of Sir Walter Scott’s Waverley Valley, by the urban viaduct, North Bridge, and by the Mound, creates the outstanding urban landscape.
Edinburgh, the capital of Scotland, falls into a category of World Heritage Site where the entire city gets lumped into one site. You can find similar sites in Rome, Paris, Kyoto and Budapest.
The architecture of the city has a very powerful feeling which is highlighted by the castle overlooking everything.
I only had one day in Edinburgh and it was in the winter, which limited my daylight exploration hours. I very much wish to return in the summer so I can better explore the city and its buildings.
View my complete list of UNESCO World Heritage sites.