On the island of Gogland, Struve established a unique station in 1826 that connects two continental chains of triangles, separated by the Gulf of Finland, into a single measurement. One of the island’s attractions is point “Z.” This is an astronomical-geodetic station laid out in 1826 upon the completion of the meridian arc measurement in the Baltic provinces of Russia. From the Myakipyalyus cliff on Gogland, Struve observed angles and azimuths, and at Point Z — the astronomical latitude. The Gogland Point Z station is located at the foot of a hill 700 meters west of the Suurküla harbor, at an altitude of 30 meters above sea level. On site, the station is marked by a stone monument, beneath which lies a core extending one meter beyond the stone masonry. On the ground, one can also see the physical remains of two supporting brick pillars that held Struve’s telescope in 1826. A memorial plaque describes the role of this station.

The Struve Arc, once known as the “Russian” and later the “Russo-Scandinavian Meridian Arc,” is one of UNESCO’s World Heritage monuments. The arc consists of 265 triangulation points, along which measurements were conducted from 1816 to 1852, enabling the precise determination of the Earth’s size and shape.

The reference points of this triangulation network were marked in various ways on the terrain: hollows carved into rocks, iron crosses, stone pyramids, or specially installed obelisks. Often they were marked with sandstone bricks laid at the bottom of a pit; sometimes it was a granite cube with a cavity filled with lead, placed in a pit with cobblestones.

During the 8-year project to include the Struve Arc in the UNESCO list, special search and geodetic works were carried out in each country to locate the original points. All information from all the countries of the Struve Arc was collected, structured, and standardized.

Not all of the original points were found during the special search and geodetic works carried out in recent years with active cooperation among scientists from the interested countries, and many of them were found to be heavily damaged. Therefore, only the best-preserved points — a total of 34 — were included in the World Heritage site.

Sources:

http://www.gototrip.com/publications/geodezicheskaya-duga-struve

https://roscadastre.ru/html/II_sezd/19_%D0%A2%D0%B8%D1%85%D0%BE%D0%BD%D0%BE%D0%B2%20%D0%92.%D0%92.pdf