Nissa Raatko, Doctor Mist, and Hugo Danner established the Cairo Club in 1930 specifically to oppose Ra's al Ghul, Vandal Savage, and General Immortus who were attempting to bring the world to a global cataclysm and split the remains. Raatko sought out Danner after her father's organization – the Demon's Hand – identified Danner as a possible heir to the empire and Ra's in turn discounted him as too jingoistic-ly idealistic. Danner acquired the Blue River (Wedjet Phiaro) from
Lee Granger - an old friend he'd met in the Legion. Lee provided the staff and help.
Danner brought Kip Islington – who he also knew from the Foreign Legion - in as a bartender and occasional support. This is before Islington lost his memory and started wandering the battlefields of WWII.
Carter Hall, originally from Detroit, and Kent Nelson, the son of an archaeologist from Cleveland, met in college in New York then wound up working with Louis Sendak who was originally from New York, in the field. They ran across the Saunders Girls during a wild night in Morocco fighting followers of the Religion of Crime and the five were just about inseparable there-after. The Batsons (with Theo Adam) and Andrea Thomas were all from Chicago and met on the boat from New York to LaHavre. The Batson team and the New York Boys met at the Blue River. They were introduced by Lee Granger who was already involved. John Sargent and Ed Dawson (and Dawson's assistant Pan) had worked together in Philadelphia and met again in Istanbul, where they began collaborating again. Lee Granger convinced them to come to Cairo and they joined the Club soon after. Vandal Savage and Ra's al Ghul were the main reoccurring villains. It was Savage's scheming that encouraged Hath-Set and led to the fall of Prince Khufu and the imprisonment of Shazam and Nabu. He again showed up in Egypt between the wars fighting the Cairo Club, then working for the Nazis in WWII.
Everything from ancient civilizations and militant gorillas to mummies and the occasional dragon got dealt with. This is also BEFORE anyone had powers or became a recognized hero. It all fell apart by inches in the end. Dr. Minerva was the first to disappear – into the jungles of Deepest Darkest Africa – then Andrea Thomas on a dig in Egypt. Pandora Pan got involved with an artifact in Mesopotamia while Ed Dawson would find a meteor/alien device in Iran soon after. One day Islington just wasn't there and Karkull and Dahlen followed a rumour out into the Sahara and never returned. In Egypt the Batsons were betrayed by their partner Theo Adam, Kent Nelson and Inza Saunders got swept up in the schemings of a lost god, and Carter Hall and Sheira Saunders had a bad flashback under the shadow of the pyramids and went off to discover their past selves. When Louis Sendak discovered the blue scarab that was pretty much it; Congo Bill returned to the Congo, Rick Nelson (and his ward Lionboy) went back to America that was the end of the Cairo Club.
Nyssa and Bogdan returned to Slovenia to join the resistance and in time raised two daughters, but ended up in a concentration camp. Danner figured to hell with it all and fled to South America as Doctor Mist simply walked out of history yet again. They hadn't prevented the war but they had kept things from getting anywhere near as bad as they could have. It was now a time for soldiers, not adventurers.
Instead of emptying or tearing down the Blue River Doctor Mist placed a gease on the building that caused interest and focus to just drift over it. No one wanted to explore or vandalize it, no one thought to buy or renovate it. While the building had belonged to Lee Granger he had sold it to Hugo Danner who in turn left it to his son Arnold.