• Post category:Articles
  • Post published:31.1.2023

The Struve Geodetic Arc is a shining pearl among UNESCO World Heritage Sites

The Struve Geodetic Arc stretches from the European side of the Black Sea all the way to the Arctic Ocean. Finland’s northernmost World Heritage Site is located at the top of Stuorrahanoaivi in Enontekiö. Photo: National Land Survey of Finland.


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The Struve Geodetic Arc stretches from the European side of the Black Sea all the way to the Arctic Ocean. Finland’s northernmost World Heritage Site is located at the top of Stuorrahanoaivi in Enontekiö. Photo: National Land Survey of Finland.

Congratulations, you have received heritage! Not just any heritage, but World Heritage. You do not need to pay any inheritance tax or worry about registering the transfer of ownership.

Since 1972, sites that carry a significant value as unique culture and natural heritage sites have been added to the UNESCO World Heritage List, which includes sites in nearly 200 countries. Keeping heritage sites in as original and authentic condition as possible is the common cause of all humankind. They convey knowledge, skills, conceptions and traditions to us. Currently, there are seven UNESCO World Heritage Sites in Finland.

Being added to the list is the result of a long-term process, during which the authenticity and significance for science and culture, for example, are identified under close scrutiny. Furthermore, it is not self-evident that a site remains listed. During last summer, the removal of the Liverpool waterfront from the World Heritage List due to the construction of the Everton football stadium was discussed onvarious media platforms. At the same time, Old Rauma, a World Heritage Site in Finland, is having similar problems: a modern shopping centre is defying the idyllic wooden centre.

In addition to Old Rauma, Finland’s World Heritage Sites include the Fortress of Suomenlinna in Helsinki, the Petäjävesi Old Church, the Verla Groundwood and Board Mill in Kouvola, the archaeological site of Sammallahdenmäki in Rauma, the Struve Geodetic Arc, and the Kvarken Archipelago. Building architecture by Finnish architect Alvar Aalto and the Ringed Seal Archipelago of Lake Saimaa are seeking a place onthe list.

What is the Struve Geodetic Arc?

The Struve Geodetic Arc is a chain like structure that resembles a gigantic tape measure, which was used to verify the shape and size of Earth in the 19th century. It was used to determine the length of the meridian arc from the Black Sea to the Arctic Ocean, totalling at 2,820 kilometres.

The chain was determined based on triangulation. In triangulation, the unknown lengths of two sides of a triangle can be calculated based on the angles of the triangle if the length of one side is known. Triangulation networks consist of points that form several triangles.

The scale of the chain was determined using baselines, which are lines of a few kilometres, the length of which is known at the accuracy of millimetres. The shape and size of the chain was calculated based on the lengths of the sides of the triangles and observations of their angles. The actual location of the chain and its position relative to Earth’s surface were determined usingstronomical positioning.

Administrative cooperation and networks

The Struve Geodetic Arc passes through ten countries. In Finland, it is under the management of the NLS.

The Struve Geodetic Arc was inscribed on the UNESCO World Heritage List in 2005. The administrative authorities of the ten countries work together every year to ensure the preservation and authenticity of the site, also internationally. The UNESCO World Heritage Committee monitors the listed sites actively, and all maintenance and administrative measures must be reported to UNESCO.

The factors that threaten authenticity have changed along the years, and they vary from one country to the next. Currently, wind farms are a hot topic around the Struve Geodetic Arc, especially in the Nordic countries. How can the generation of renewable energy be smoothly combined with the preservation of world heritage?

In addition to the NLS, the Finnish Heritage Agency and the Association of World Heritage Sites in Finland are driving forces behind the Struve Geodetic Arc. They play an important role in the World Heritage Centre project in Central Finland, in which a new round-the-year visitors’ centre will be built next to the Petäjävesi Old Church. The aim of the centre is to provide information not only about the Petäjävesi Old Church, but also about the Struve Geodetic Arc and UNESCO World Heritage principles in general.

One of the triangulation points of the Struve Geodetic Arc is located in Oravivuori, Korpilahti, Jyväskylä, which will benear the World Heritage Centre yet to be built. The accessibility of the Oravivuori point was tested last summer by preparing a paper and digital route guide for the area.

Struve North strengthens cooperation in the northern parts of the chain

Struve North is a three-year cooperation project between Finland, Sweden and Norway. Its goal is to increase knowledge of the Struve Geodetic Arc and improve its accessibility. At the same time, it strengthens Nordic cooperation and the vitality of the area. The NLS participates in the project as a guiding specialist and partial funding provider.

In Lapland, the triangulation pointsare sparsely spread over an area of difficult terrain , and various digital solutions based on geospatial data are used to increase their visibility.

Welcome to the virtual world, says Mr Struve

The Struve North project has also carried the Struve Geodetic Arc into virtual reality. Drone videos and 360° photos of the triangulation points have been entered in a game environment, where they can be explored using a VR headset. For example, museum visitors can access the triangulation points in a virtual 3D world. In virtual reality, visitors can also try their hand at triangulation by using a measuring instrument in the surroundings of the Alatornio Church.

The aim is also to use ultrahaptics technology, which enables the touchless control of screens. A student of visual arts from Lapland University of Applied Sciences has re-animated Mr Struve  who now acts as a guide in the touring exhibition using an ultrahaptics device.

Steps of Struve mobile game, in which players can travel north from Tornio while solving puzzles, is available on app stores.

In addition to digital solutions, the Struve North project underlines the significance of world heritage as an asset for productisation and learning. In the winter, comprehensive schools in the northern region were able to learn more about the ‘Haluatko tutimusmatkailijaksi?’ (Would you like to be an explorer?) concept piloted by Humak University of Applied Sciences, and several schools are now organising field trips to the triangulation points with an adventure-based approach. In addition, various webinars and workshops have been held for companies.

Welcome to the wondrous world of the Struve Geodetic Arc!

Eila Seppänen is a coordinator of the Northern Parts of the World Heritage Struve Geodetic Arc (Struve North) project at Lapland University of Applied Sciences. Email: firstname.lastname@lapinamk.fi

Ulla Mikkanen works as World Heritage Coordinator at the NLS. The NLS manages the Struve Geodetic Arc in Finland. Email: firstname.lastname@nls.fi

Timo Saari is a senior research scientist at the Finnish Geospatial Research Institute (FGI) of the NLS. He is a member of the research group that studies Earth’s gravitational field. Email: firstname.lastname@nls.fi