They had waited in the passage to the air lock. Now Matt pulled himself together, ran to the port and threw it open. Fort Knox had been moved since World War II. The atom bomb had made a large army, navy or air force obsolete. The barracks of the old fort had been enlarged and modernized and, at the time of the plague, housed workers who commuted back and forth to Louisville. The gold vault had been turned into a museum and library, the parade ground into a park. New Fort Knox was a single massive building of gray monolithic concrete. Large as a city block and thirty stories high, the frowning structure was located on a promontory overlooking the Ohio and Salt rivers. It had housed a detachment of the world police, and the laboratories and living quarters of the technicians who had come to replace the standing army in the new era of push-button warfare. Matt, staring at the cubical gray fort, realized that it had been built to protect the lethal experiments that had been carried out in its labs. There were no windows on the first or second floors. Nothing less than an atom bomb could destroy it. He cast a cautious glance at the silent deserted town of West Point beyond the highway and the brown slack waters of Salt River, muddied by spring rains. The _Argus_ had landed directly behind the fort and the Ohio was at their backs. Isaac Trigg came into the passage with Captain Bascom. Rapidly the others began to assemble. "Well?" asked Isaac. "Look for yourself. We could have scoured the world and not found a better place." They crowded to the port, staring out at the silent pile of concrete. "Splendid! Splendid!" Isaac rubbed his dry hands together. Broad grins, laughter and exultant comments broke out among the others. Isaac gazed fondly at Matt. "You're the boss, Matt. What's to be done?" "Strip the _Argus_ of everything that can be moved and carry it into the fort. There should be guns in there and ammunition. It housed a detachment of the world police force, you remember. They used the obsolete weapons--never resorted to A-bombs unless necessary. "We've crossed Salt River, but not the Ohio. That means we'd better destroy the monorail and the tube crossing and the railway bridge. We can leave the highway bridge up, but we'll have to fortify it temporarily." "Then," broke in Captain Bascom, "you think the Amazons will follow?" Matt nodded. "They could see us come down not too far off." He paused, pushing his hand through his short black hair. "But we were north of Salt River. Now we're south of it. They can't know that. Neither can they know whether we've crossed the Ohio or not. I imagine they'll send scout cars." "That bridge"--he pointed to the arches spanning the Salt river--"is the only one this side of Shepherdsville.