The Duke Cave is a secret command center in Duke Nukem Forever used by Duke Nukem for monitoring events around the world. It is equipped with multiple computers and data on enemy aliens and television monitors for instant communication with important figures like General Graves and the US President. The Duke Cave is furnished with recreational facilities and certain amenities, like a fridge full of beer. There also seems to be an automated system (with a feminine voice) that serves as a caretaker for the Duke Cave when Duke is not present, as it is shown informing him of the Duke Cave's status during the alien attack on Vegas; it also complements him when he restores power to the cave.
The Duke Cave seems fully prepared to defend itself and the immediate Vegas area, as it is stocked with items and weapons Duke can use in the event of an attack. Such items and weapons include steroids, to temporarily but vastly improve Duke's strength, and a safe holding Duke's gold-plated M1911 pistol. Most impressively, it is equipped with a quad-barreled anti-aircraft laser turret that retracts toward the roof of a building. It is powerful enough to destroy advanced alien aircraft and even a colossal alien Mothership, as seen during Duke's battle with the Mothership.