The stone walls of Intramuros, Manila, are 8 meters thick
The Walled City of Intramuros was built towards the end of the 16th century by the Spanish. The 4 kilometer wall which runs around the perimeter was started in 1584 and took 6 years to complete. Chinese laborers built the wall. When it was complete, the only access to the walled city was through a series of gates. In short, the Spanish protected themselves well.