permanent base stations. Hong Kong Many trigonometrical stations were placed on hilltops around Hong Kong. They strongly resemble those used in other British colonial territories such as Australia, consisting of a white column topped with a black band. Japan In Japan, there are five classes of : They are installed approximately every , with smaller ones (as necessary) about every . There are about 1000 throughout Japan. The pillars are on a side, and each pillar is anchored with two very large perpendicular rocks buried underground. They are installed approximately every . There are about 5000 throughout Japan, and the pillars are on a side. Each pillar is anchored with a very large perpendicular rock buried underground. There are about 32,000 installed throughout Japan, with one approximately every . The pillars are on a side, and each pillar is anchored with a large perpendicular rock buried underground. They are installed approximately every , and there are about 69,000 throughout Japan. The pillars are on a side, and each pillar is anchored with a large perpendicular rock buried underground. These markers were installed in 1899 and are the predecessors to the modern triangulation stations used in Japan today. They are generally not used anymore since the installation of the Class 1-4 stations. Some of them still exist at various locations throughout Japan. South Africa South Africa has a network of approximately 28,000 trig beacons, established by the Chief Directorate: National Geo-spatial Information (historically known as the Trigonometrical Survey). These beacons are typically white-painted concrete pillars supporting black metal plates in a cross shape, installed on mountains, hills or tall buildings. Spain In Spain there are 11,000 triangulation stations, concrete buildings which typically consist of a cylinder 120 cm high and 30 cm diameter over a concrete cubic base. They were erected by the Instituto Geográfico Nacional, usually painted in white, and can be marked with a metallic label with the warning: "The destruction of this sign is punishable by law." United Kingdom In the United Kingdom, trig points are typically concrete pillars and were erected by the Ordnance Survey. The process of placing trig points on top of prominent hills and mountains began in 1935 to assist in the accurate retriangulation of Great Britain. The Ordnance Survey's first trig point was erected on 18 April 1936 near Cold Ashby, Northamptonshire. In low-lying or flat areas some trig points are only a