First triangular point "Nagatsuda Village"

In the Meiji era, first triangular points were set up nationwide with the aim of grasping the national land with unified standards and high accuracy. The triangle triangulations made at the first triangle point was repeated, and the first triangle net, which was the framework of the map, was created. The only first triangular point in Yokohama is Nagatsuda Village, located on the summit of Mount Takao.

Triangle surveying is a survey method that measures the angle of the triangle and calculates the size of the triangle by calculation. For this reason, the first side (baseline), which is the basis for subsequent calculations, was measured as a straight line.
Based on the Sagamino Baseline (*), which was observed at 5209.9697m in 1882 as the bottom, a triangle with the first triangular point "Nagatsuda Village" as the first expansion point (vertex of the triangle) was connected. It was connected to the first-class triangle net covering the whole country.

After that, over 30 years, the basic map of the national land, will be developed over 30 years, but efforts to grasp the land with unified standards and high accuracy have begun here.

The signpost of "Nagatsuda Village" is 83.2cm long and weighing about 90kg buried in 1883.

※Sagami Field Baseline: A straight line connecting the first triangular point "Shimomizo Village" (Sagamihara City's designated cultural property "Sagamino Kisenkita End Point" and the first triangular point "Zama Village" (Zama City Designated Important Cultural Property "Sagamino Baseline South Exit"). It was observed at 5209.9697m in 1882 It has become a selected civil engineering heritage of the Japan Society of Civil Engineers as "the birthplace of modern surveying in Japan".

　　　　　　　　　　　　　▲First triangular point "Nagatsuda Village" markstone

▲1st triangular point

[View from Mount Takao]
On a sunny winter day, you can see the mountain ridgeline.

▲From the vicinity of the summit of Mount Takao (photographed on February 10, 2021)
※The name and location of the mountain are approximate.

▲To Mount Takao (Hachioji City, Tokyo) from Mount Takao Mountain Road (Photographed on February 10, 2021)

※The name and location of the mountain are approximate.

5617, Nagatsutacho, Midori-ku, Yokohama-shi

[Bus Route]
From JR Yokohama Line / Tokyu Denentoshi Line Nagatsuta Station (South Exit)
From Minamimachida Station (North Exit) on the Tokyu Denentoshi Line

■Take the Kananaka Bus [Tsu 1] and get off at the bus stop "Takahara" bus stop and walk 10 minutes.