After the 13th century no major monuments seem to have been constructed at Chichen-Itza and the city rapidly declined after around 1440 A.D. Criterion (ii): The monuments of Chichen-Itza exerted an influence throughout the entire Yucatan cultural zone from the 10th to the 15th century. Criterion (iii): Chichen-Itza is the most important archaeological vestige of the Maya-Toltec civilization in Yucatan (10th-15th centuries). This means that the site needs constant maintenance and attention in order to avoid deterioration of its prehispanic fabric. Medium and long-term activities at Chichen-Itza, including investigation, conservation, thematic interpretation, administration and operation of the site, are addressed in the "Management Plan of the Pre-hispanic City of Chichen-Itza".