Ligñon Hill is a prehistoric cinder cone near the foot of Mayon, some 12 kilometers south-southeast of the volcano's summit. It is mainly composed of dolerite and basaltic volcanic rocks. Except for Mayon Volcano, it is the highest point in the city situated next to the Legazpi Airport in barangay 41 (Bogtong) near the city's border with the municipality of Daraga. It hosts the Mayon Volcano Observatory, the central monitoring station of the Philippine Institute of Volcanology and Seismology built in 1989.