In this study 294 HMS were assessed, 84 HMS in the study area of six zones were assessed as damaged by flood in 2011 and are shown in figure 9 [19]. For the remaining 210 HMS damage assessment was carried out considering the limitations of the historic monument sites survey of damage, and some HMS were assigned to undertake renovation. The field survey of flood impacts in Ayutthaya on October – December, 2011 and drainage of moisture in the soil needs time to prevent damage to the structure of the historic monument sites.