The Struve Geodetic Arc is a series of triangulations done by Tartu University astronomer and geographer Friedrich Georg Wilhelm Struve between 1816 and 1855. The measurement of the meridian, which used the observatory at Tartu University in Estonia as its base point, represented the first accurate measuring of a long segment of a meridian. This helped to establish the exact size and shape of the planet and marked an important step in the development of earth sciences and topographic mapping.
Struve was an astronomer at Tartu University and did important early astronomy work on the nature of binary stars. But his actual thesis work was on determining the exact coordinates of the Tartu Observatory. This, indirectly, led to his geodesic project.
You can certainly click the link above, and here for some more info on the Geodesic Arc, and it's status as a Unesco World Heritage Site.
I, with my limited knowledge of math and physics, find the work of people such as Struve, accomplished around 200 years ago, simply astonishing. We love visiting Unesco sites in general, but the scientific ones are maybe even more interesting to me than the artistic and historical ones.
For an interesting read on geodesic mapping, I also suggest a book about a similar project carried out in South America, before Struve's work was done. A similar project, with similar aims, to determine the size and shape of the earth, done by a French and Spanish team almost a hundred years before Struve. The book is called The Mapmaker's Wife: A True Tale of Love, Murder, and Survival in the Amazon and weaves the story of the mathematicians' quest with some stunning personal stories. I read it while we lived in Ecuador. I highly recommend it.
The Observatory and marker of the Struve Geodetic Arc are a UNESCO World Heritage site in Estonia.
Tom, We have been trying to hit one of the Struve Geodetic Arcs, but they are always so far away! Maybe Tartu, when we go to Estonia. As teachers, we also really love the scientific World Heritage Sites, but really we love them all!
Of all the Struve sites, this one is probably the best. The observatory itself, which is now an historic museum is very interesting. Many of Struve’s instruments are on display. My understanding is that most of the Struve sites are just markers on the ground. This one has lots to offer.