Montero Cave System

The Montero Cave System is an immense series of caves located beneath the surface of Gao, a human Outer Colony. Located in the Montero region in the Campos Wilderness District, the cave system encompasses thousands of square kilometers of karst caves underneath the Montero Jungle.

Overview
The Montero Cave System was host to the Forerunner Covert Support Base 4276, a support facility for Line Installation 444-447 on the nearby Shaps III in the Shaps system. The cave system itself—at least the portion of it around the support base—was artificial, created by the Forerunners to function as service caverns for the facility. The caves served as a camouflaged cooling array, with the winding tangles of caves seemingly designed to give hot air time to cool before it reached the surface. The caverns rose upward in a roughly spiral pattern, many of them terminating at underground lakes. In the center of the elaborate array was the Well of Echoes, a deep basin directly above the Forerunner base, which served as a vent for the hot air. Other parts of the caves performed various functions for the support base, including drainage conduits and settling ponds—all camouflaged to appear natural.

Its nature unknown to the human colonists, the Montero Cave System was Gao's most popular natural wonder and a famous tourist attraction. During Operation: JOVIAN WHISTLE on July 6, 2553, the support base and a large part of the cave system around it were destroyed by Blue Team with a HAVOK tactical nuclear weapon to prevent the Forerunner technology from falling into the hands of the Gao Republic's anti-centralization government.

List of appearances

 * Halo: Last Light
 * Halo Mythos