Struve geodetic arc is part of the history of science and technology. It’s an UNESCO World Heritage feature that’s located in ten countries stretching from Arctic Ocean to Black Ocean. The countries are Norway, Sweden, Finland, Russia, Estonia, Latvia, Lithuania, Belarus, Moldova and Ukraine. German-born Russian scientist Friedrich Georg Wilhelm von Struve used it during 1816 – 1855 to determine the Earth’s size and shape using triangulation. The arc had 265 measurement points spanning over 2800 km. 34 of them are UNESCO protected sites since 2005. Six of them are located in Finland, one of them in Oravivuori, at coordinates 61°55’36″N 25°32’01″E. Oravivuori has a ten-meter high observation tower and there you can see nicely the Lake Päijänne landscape surrounding the site.