First class triangular point "Nagatsuda Village"

Meiji period has established first-class triangular points nationwide with the aim of understanding the country with uniform standards and high accuracy. Triangles of triangles made at first-class triangular points were layered, and a first-class triangular net, which is the framework of the map, was created. The only first triangular point in Yokohama City is Nagatsuda Village on the summit of Mt. Takao.

Triangle measurement is a surveying method that measures the angle of the triangle and calculates the magnitude of the triangle by calculation. For this reason, the first side (baseline), which is the basis for subsequent calculations, was actually measured as a straight line.
With the Sagamino Baseline (*), which was observed at 5209.9697m in 1882, the triangle was formed in 1883 with the first triangular point "Nagatsuda Village" as the first increase point (the top of the triangle). It was connected to a first-class triangular network covering the whole country.

After that, over 30 years, a 1/50,000 topographic map, which is the basic map of the national land, will be developed, and efforts to grasp the national land with unified standards and high accuracy have started here.

The pillar of "Nagatsuda Village" remains a stone buried in 1883 with a total length of 83.2 cm and a weight of about 90 kg.

※Sagamino Baseline: It is a straight line connecting the first-class triangular point "Shimomizo Village" (Designated Cultural Property Sagamino Kisenkita end point in Sagamihara City and the first-class triangular point "Zama Village" (Zama City designated important cultural property "Sagamino Baseline South end point"). It was observed at 5209.9697m in 1882. It has become a civil engineering heritage selected by the Japan Society of Civil Engineers as the birthplace of modern surveying in Japan.

　　　　　　　　　　　　　▲First-class triangular point "Nagatsuda Village"

▲First class triangular point

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

▲The Tanzawa Mountains from near the summit of Mt. Takao (taken on February 10, 2021)
※The name and position of the mountain are approximate.

▲From the Mt. Takao mountain path toward Mt. Takao (Hachioji City, Tokyo) (taken on February 10, 2021)

※The name and position of the mountain are approximate.

5617, Nagatsutacho, Midori-ku, Yokohama-shi

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

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