Visiting your first component of the Struve Geodetic Arc is a rite of passage for a WH Traveller: it marks the moment that you have gone from a tourist enjoying the sights of the world into a nerd obsessed with the quirky details of lists. I have visited components of the Arc in several countries over the years. But I had not yet been to the place where Struve started it all and where some of the more interesting remains lie: Estonia.

Born in Altona (near Hamburg, but at the time under Danish rule) in 1793, Struve emigrated with his parents to the Russian Empire. More specifically, to Livonia, an area that was later divided between Estonia and Latvia. He studied at the University of Dorpat (now Tartu) and became a Professor of Mathematics and Astronomy there. It was during this period that he started his geodetic surveys in a small area around Tartu. Later on, even becoming the director of the Tartu Observatory, he obtained funds to extend his surveys further north and south and to further develop his equipment. The full measurements of ‘his’ Arc were only completed in the 1850s, requiring lots of international scientific cooperation and funding. The Nomination Dossier especially highlights the “considerable amount of international labour under various climatic, topographic and geographic circumstances”.

What Struve and his colleagues tried to do was to determine the size and shape of the earth by way of triangulation. How they did this precisely is explained in Appendix I of the Nomination Dossier, but my mind always automatically shuts down while processing geometric shapes with ABCD-labels attached, so I cannot retell it here. Important to know, however, is that in Estonia, the locations Woibifer (#17) and Katko (#18) are the terminals of a kind of ‘support line’: the short Simonis baseline. The accurate measurement of this baseline was key to calculating the longer distances between the points.

So to Katko and Woibifer I went first. I reached Katko by driving 1.5 hours south of the Baltic Klint TWHS. The drive goes through a quiet area, mostly forest with some farms here and there. A bit like Finland, but not as dramatic. The Struve marker is signposted from the road. There is no real parking, but the roadside shoulder provided enough shelter for my one-minute visit. The site is neatly maintained: it has an information panel, a plaque and a granite stone marker of unknown date ("some long time back" according to the Nomination Dossier). The grass around it has been mown. Just as with so many of the other markers, no original remains from Struve’s time are visible. What we now see and “celebrate” is the accurate coordinate, adorned with a monumental marker of a later date.

Just some 5km away lies its sister site Woibifer. Also signposted, but a bit hidden from sight, as it lies at what looks like the backyard of someone’s home. It is next to an old windmill. The marker here is covered by a plexiglass dome. The granite in the middle apparently has the original drill hole, which has been rediscovered and dug out.

Here also, despite the limited space, there is a plaque and an information panel. After having seen many of these minor Struve locations, I am always amazed to see that they are still cared for, possibly by some volunteers from a nearby university.

I stayed overnight in Tartu, about 75 minutes further south, and the next morning I walked up the hill to the Old Tartu Observatory (the final of 3 Struve components in Estonia). This is actually Point Zero of the whole Arc: Struve used Tartu Observatory's location on the 27th meridian East of Greenwich as the foundation for the rest of his measurements. The observatory is located in a well-preserved neoclassical building. In the park in front of it is a sculpture dedicated to Struve and his works. Walking here, it feels like you're on a pilgrimage to honour the Struve's work ánd this quirky WHS. There's a plaque, lots of banners, and souvenirs for sale with the man's image!

The interior of the Observatory is worth a visit too, although not everything inside revolves around Struve's geodetic works. Next to measuring the Earth, he was also an important astronomer. The first room has a multimedia display about how the triangulation process worked, explained with cartoon-like scenes; so this time I (almost) fully understood!

I do believe I have come full circle now - having read the nomination dossier (well-worth it, with fascinating details such as that Struve used the old French "toise" as unit of length), visited the exhibition in Tartu and seen a variety of measuring points. But wait... that monumental endpoint in Hammerfest looks cool too! So maybe these Estonian ones won't even be my last Struve sites to visit...