Vigan has maintained its authenticity in its grid street pattern, historic urban lay out and use of open spaces. The historic buildings have maintained their traditional uses for commerce at the lower floors and as residence for the owners on the upper floors. However, very few houses remain untouched. Changes introduced to the betterconserved houses have been to the interior: subdividing the large living quarters into smaller apartments, and adjusting of ground floor to provide spaces to let out for commercial use. After having been completely altered to allow new uses, many structures have lost their authenticity. A few structures have been abandoned, neglected, and left to decay. The original building materials such as bricks, wood, kapis shells and lime for mortar and plaster were all obtained from surrounding areas.. The lack of traditional building materials such as wood and lime for plaster and mortar has resulted in the use of modern materials such as cement and galvanized iron sheets for roofing. The awareness on the need to preserve authenticity has dramatically increased since the site was inscribed. Conservation practices that have developed organically over the last three centuries are now being re-introduced, making use of a considerable reserve of traditional building crafts that have survived”.