At the beginning of the 2oth century, the Metro Manila city of Valenzuela was known before as the rural town of Bulacan called Polo. South of Polo was a bustling fishing town called Malabon, one of the many towns that comprised the then-newly established Province of Rizal.
To demarcate the boundary between the two provinces, the American colonial government built in 1910 a stone arch along what was then the main thoroughfare to Northern Luzon. It was no grand structure or anything but it served its purpose. Locally it became known by the name which is how “stone arch” is known in Tagalog: Arkong Bato.