The Struve Geo­det­ic Arc is a chain of sur­vey tri­an­gu­la­tion mea­sure­ments stretch­ing from the Arc­tic Sea to the Black Sea, through ten coun­tries and over 2,820km. These are points of a sur­vey, car­ried out between 1816 and 1855 by the astronomer Friedrich Georg Wil­helm Struve, which rep­re­sent­ed the first accu­rate mea­sur­ing of a long seg­ment of a merid­i­an. This helped estab­lish the exact size and shape of our plan­et and marked an impor­tant step in the devel­op­ment of earth sci­ences and topo­graph­ic map­ping. It is an extra­or­di­nary exam­ple of sci­en­tif­ic col­lab­o­ra­tion among sci­en­tists from dif­fer­ent coun­tries, and of col­lab­o­ra­tion between mon­archs for a sci­en­tif­ic cause. The orig­i­nal arc con­sist­ed of 258 main tri­an­gles with 265 main sta­tion points. The list­ed Unesco World Her­itage site includes 34 of the orig­i­nal sta­tion points, with dif­fer­ent mark­ings, i.e. a drilled hole in rock, iron cross, cairns, or built obelisks.
The Struve Geo­det­ic Arc is a UNESCO World Her­itage Site. Six of the sta­tion points that have been select­ed to rep­re­sent the entire Arc on the World Her­itage List are locat­ed in Fin­land. The sta­tion points have his­tor­i­cal impor­tance, but they also offer excel­lent views of the sur­round­ing area.
The Struve Geo­det­ic Arc has also been called the Rus­­so-Scan­di­­na­­vian merid­i­an mea­sure­ment, because orig­i­nal­ly the Arc remained with­in two empires.