Ecole Franchise d'Extreme-Orient (EFEO) has made restoration in Angkor monuments since 1907 and recorded a lot of documentary about the causeway of Angkor Wat in Rapport sur les travaux executes dans le groupe d'Angkor. EFEO made a part restoration, not all, the southern side of the causeway of Angkor Wat in the 1960s. The remained part, the northern side, is now making restoration and researched here at the same time in order to make the structure of the causeway of Angkor Wat clear in view of masonry technique. The results had a lot of respects through dismantling and excavation, taking a data about structure problems and show us that Khmer engineers had many experience, knowledge and a skillful technique handling with Stones including soil improving to prevent the western causeway from rains.
