Somewhere in the Latvian countryside, on a modest rise above the Daugava, stands a marker that was once part of the most ambitious measuring job of the nineteenth century. Sestukalns is one of the stations of the Struve Geodetic Arc, a chain of triangulation points that runs for nearly three thousand kilometres from Hammerfest on the Arctic coast of Norway to the Black Sea. The astronomer Friedrich Georg Wilhelm Struve, working out of the observatory at Dorpat, now Tartu, led the survey between 1816 and 1855 to find the size and shape of the Earth, and the result was accurate to a degree that astonished geodesists. It is on the World Heritage list, with a few dozen of the stations that still survive across ten countries.
Nothing about the landscape is dramatic, and that is exactly why the arc worked: Latvia is gentle, with low ridges, pine woods, farms and slow rivers, and its sky is wide. The Daugava, the great river that runs from Russia past Daugavpils and Jekabpils to Riga, has been dammed in several places, and the stretch near Koknese and Plavinas was drowned by reservoirs in the twentieth century, so the old rapids lie beneath the water. The ruins of the medieval castle of Koknese stand on a promontory above the reservoir. The rides that use this stop link the Struve station with the old town of Jekabpils, known in German as Jacobstadt after Duke Jacob of Courland, and with the historic centre of Riga.
On a motorbike, Latvia is easygoing rather than dramatic. The main road along the Daugava, the A6, carries trucks and cars at speed, so the quiet side roads are more pleasant, with gravel in places, farmsteads, storks nesting on poles in summer and long straight avenues of birch. Police patrol, and speed limits drop sharply near villages. Expect long summer evenings in June, when the sun barely sets, and flat, golden light in September, with mushrooms for sale along the verges. Winter is cold and dark, with snow and ice.
Aizkraukle, some thirty-five kilometres away, is the nearest sizeable town, with fuel stations, shops and cafes, and Jekabpils on the other bank has a similar range. Out in the villages, services are scarce, so top up when you can. Try rye bread, smoked fish, pirags, the bacon-filled bread rolls, and a glass of kvass or a local beer at a roadside cafe. Riga is about a hundred and twenty kilometres to the north-west, an easy ride on the main road.