This image was acquired from
wikimedia. It was marked as Public Domain or CC0 and is free to use. To verify, go to the source and check the information there.
Keywords from Image Description:
First Triangular Surveying of Sasago Pass. ja en Map showing first triangular surveying of Sasago pass Yamanashi Japan Survey for construction of Sasago tunnel of Chuo mainline conducted in Imperial Japanese Government Railways Custom marker PDJapanorganization Uploaded with Sasago Tunnel Ch Main Line Triangulation