Vilhelma Strūves Street 6, Jēkabpils, LV-5201, Latvia
The Jacobstadt point was established in May-June 1826.
This point is located in the historic center of the city of Jēkabpils, in the city park named after Friedrich Struve. The park covers an area of 1.2 hectares, and the adjacent street is called Struve Street in honor of the achievements of the outstanding geodesist and astronomer Friedrich Georg Wilhelm Struve. This is one of the most important points of the Struve Geodetic Arc in Latvia. There are a total of 16 such points. Over time, the residents of Jēkabpils have taken care to ensure that the point was not destroyed. In 1931, it was reinforced and covered with a commemorative stone. The stone was presented to the city as a gift by the natural science teacher Eduards Valters from the Jēkabpils Gymnasium. A 42-meter triangulation observation tower was built over this point, but it has not survived. A stainless steel memorial plaque with information about the geodetic arc and a map of the 16 historic points located in Latvia was installed on June 17, 2006, with the aim of popularizing and preserving the Jacobstadt point of the Struve Geodetic Arc, which is an object included in the UNESCO World Heritage list. Opposite the memorial plaque, a symbolic triangulation tower was installed.
The Struve Arc, once known as the "Russian" and later the "Russo-Scandinavian Meridian Arc," is one of the UNESCO World Heritage monuments. The arc consists of 265 triangulation points, along which measurements were conducted from 1816 to 1852, allowing the precise determination of the size and shape of the Earth.
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 project to include the Struve Arc in the UNESCO list, which lasted 8 years, 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 of scientists from interested countries, and many of them were found to be heavily damaged. Therefore, only the best-preserved points—34 in total—were included in the World Heritage site.
Sources:
http://www.gototrip.com/publications/geodezicheskaya-duga-struve
