Six of the Struve Geodetic Arc measurement points in Finland have been selected as UNESCO World Heritage Sites. The Porlammi station point, located on Tornikallio at lake Pyhäjärvi is one of them. The point was established in 1833 at the top of the rock Tornikallio and was marked as a drill hole in bedrock.
Unesco: Struve Geodetic Arc
RR: Big 50 - May 2025
Date: May 18
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