A scale relief map of the tadpole-shaped island of Corregidor (in the Philippines).  The island is 6 kilometers (4 miles) long and 2.4 kilometers (1.5 miles) at its widest point, with an area of 5 square kilometers (2 square miles) and a highest elevation of 121 meters (397 feet).  The island, part of an ancient volcanic caldera, divides the entrance to Manila Bay into two main passages, North Channel and South Channel.  Construction of fortifications on Corregidor began as early as 1904 as part of the Manila harbor defenses and were primarily designed to meet a seaborne attack. Click here to enlarge.