From the World Heritage inscription:
Established in the 16th century, Vigan is the best-preserved example of a planned Spanish colonial town in Asia. Its architecture reflects the coming together of cultural elements from elsewhere in the Philippines, from China and from Europe, resulting in a culture and townscape that have no parallel anywhere in East and South-East Asia.
The above photo is of the Vigan Cathedral and the central plaza. The plaza area has small models of the wonders of the world as well as a map of the Philippines with models of the Filipino World Heritage sites on it.
Vigan is a very quaint city and you can tell it is different from most cities in the Philippines the moment you step off the bus. Many of the streets in the central area do not allow automobiles. Most of the old buildings have not be renovated so you get the feel of walking through a old Spanish city.
View my complete list of UNESCO World Heritage sites.