2,820 km from the Arctic Ocean, Ending at a Village on the Danube Delta ── The Struve Geodetic Arc

45°19′54″ N. On a hill in the village of Stara Nekrasivka, near Izmail in Odesa Oblast and close to the mouth of the Danube, stands an obelisk built in the mid-19th century. It marks the southern end of a survey that ran more than 2,820 kilometres south from near Hammerfest, Norway, on the Arctic Ocean. This chain of survey points is called the Struve Geodetic Arc, and it was inscribed as a UNESCO World Heritage site in 2005.

A list of Ukraine’s World Heritage sites can be found in “Ukraine’s Cities and World Heritage.” This article looks at what the survey was for, and what remains at the four points located in Ukraine.

Measuring the Earth’s Size and Shape with a Chain of Triangles

According to the UNESCO World Heritage Centre, determining the size and shape of the Earth had been a major question of natural philosophy since at least the 4th century BC. “Triangulation” developed as a method for this. Instead of measuring a long distance directly, surveyors measure only a short baseline precisely, then work out distances by linking the angles of triangles. Chaining triangles together produces an “arc” hundreds or thousands of kilometres long.

This geodetic arc was planned by the astronomer Friedrich Georg Wilhelm von Struve (1793–1864, according to the nomination file), who worked at the University of Dorpat (now the University of Tartu in Estonia), along the meridian passing through the university’s observatory. Between 1816 and 1855, several surveyors carried out the measurements under Struve. The southern section links to an arc that the Russian imperial military surveyor Karl Tenner had already measured in Lithuania. According to Ukraine’s Great Ukrainian Encyclopedia (VUE), the two men agreed on the division of work in 1828.

The overall figures given in the nomination file are as follows: the northern end is Fuglenes near Hammerfest, and the southern end is Stara Nekrasivka near Izmail, a difference in latitude of over 25°20′. There were 258 main triangles and 265 main points. UNESCO explains that this was the first accurate measurement of a long section of a meridian, and that it helped establish the precise size and shape of the Earth.

Why were so many resources devoted to this survey? The evaluation report by UNESCO’s advisory body, ICOMOS (the International Council on Monuments and Sites), points to the need for accurate maps to fix borders in Europe after Napoleon’s defeat, and to rulers’ demand for maps for military purposes as well. VUE likewise writes that the state supported this research because the results were widely used in military topographic mapping.

In 2005, One World Heritage Site Shared by Ten Countries

The World Heritage Committee inscribed the geodetic arc as a World Heritage site at its 29th session, held in Durban, South Africa, in July 2005 (Decision 29 COM 8B.35). The nomination was submitted jointly by ten countries: Belarus, Estonia, Finland, Latvia, Lithuania, Norway, Moldova, Russia, Sweden and Ukraine. The decision recognized three criteria.

• (ii): the first accurate measurement of a long section of a meridian, marking a major step in the development of earth sciences; an example of cooperation among scientists of different countries, and of monarchs of different countries cooperating for the sake of science
• (iv): the triangulation points used in the meridian survey are an outstanding example of an ensemble of technology, representing the immovable and intangible part of surveying technology
• (vi): the survey and its results are linked to humanity’s inquiry into the shape and size of the world, and relate to Newton’s theory that the Earth is not a perfect sphere

Of the original 265 main points, 34 were included in the World Heritage site. According to UNESCO, the breakdown is: Norway 4, Sweden 4, Finland 6, Russia 2, Estonia 3, Latvia 2, Lithuania 3, Belarus 5, Moldova 1, and Ukraine 4. The combined area of the 34 points is 0.6 hectares, with a buffer zone totalling 11 hectares. The form of the markers varies by point: small holes drilled in rock (some filled with lead), crosses carved into rock, stones or bricks with embedded markers, cairns of piled stones, and monuments built to commemorate the survey.

The decision also encouraged the ten countries to consider an extension adding the arc of triangulation points measured in South Africa.

The Four Points in Ukraine

The three northern points were first observed when Tenner built a triangulation network in Podolia Governorate of the Russian Empire in 1835–40. According to the nomination file, at all three points the sightlines to other points that existed at the time have since been lost, but when the side lengths were re-measured by satellite positioning (GPS) in 2003, the results matched Tenner’s values closely, confirming that they were the same points. Commemorative monuments or plaques explaining their role were placed at the three points in 2003.

Stara Nekrasivka is the southern end of the arc, first observed by Tenner in 1851. According to the nomination file, monuments commemorating the completion of the survey were built in 1852–55 both here and at the northern end, Fuglenes, and the southern monument was centred directly above Tenner’s marker. In October 1994, a joint Russian-Ukrainian-Norwegian resurvey project carried out four days of satellite positioning.

At the time the nomination file was written, all four points were still in use as points in Ukraine’s national geodetic network. According to VUE, there are 51 triangulation points of the geodetic arc within Ukraine, running from north to south through Volyn, Rivne, Ternopil, Khmelnytskyi, Chernivtsi and Odesa oblasts. The four points that became a World Heritage site are the ones among these that are well preserved. As of September 2026, all four points lie outside the territory occupied by Russia.

An Imperial Survey, Now a Heritage Shared by Ten Countries

In the first half of the 19th century, when the survey was carried out, the land where Ukraine’s four points stand belonged to governorates of the Russian Empire. VUE writes that the project proceeded through the cooperation of the Russian Empire, Norway and Sweden, and received the support of the Russian emperors Alexander I and Nicholas I and the Swedish-Norwegian king Oscar I. The ICOMOS evaluation report assesses this geodetic arc as the most accurate of its time, the longest for more than a century, and the first arc to cross multiple countries.

Today, protection of the 34 points is the responsibility of each country. According to UNESCO, in many countries the national mapping agency manages them together with local authorities, and a coordinating committee of the ten countries meets once every two years. Based on resolutions of the coordinating committee, eight countries including Ukraine have issued stamps and envelopes for the geodetic arc. A chain of points that began as an imperial military survey has become a single World Heritage site jointly protected by ten countries.