Pontianak, a developing port city on the Indonesian side of the island of Borneo, is the largest city on the Earth’s longest invisible line, the equator.

Also known as “Equator City,” Pontianak is the capital city in the province of West Kalimantan. Standing a mere two miles north from the city center is a monument constructed to represent the otherwise conceptual equator. The spot was first marked simply with an arrow on a pole in 1928 by a Dutch geographer when he visited Borneo. The first monument, originally consisting of four wooden pillars surrounding the pole, was rebuilt ten years later by architect Silaban who turned the simple marker into a permanent monument. A globe was added to cap off the work, and a guard was added to keep it safe. A dome was finally built over the landmark in 1990 to cover the original monument and a grander replica, five times the size of the original marker monument, was added to the top.

Due to constant global shift, the monument no longer lies on the exact line of the equator. In 2005, the true equatorial line was recorded a short distance south of the monument and, according to GPS readings, the line continues to move south. Despite this increasing inaccuracy, the city of Pontianak holds a party each year during the time of the spring and autumn solstices, when the shadows of the monument and everything around it disappear at noon.