Pyramid Series by Dave Freer, Eric Flint

An alien pyramid has appeared on Earth, squatting in the middle of Chicago. It is growing, destroying the city as it does — and nothing seems able to stop it, not even the might of the US military. Somehow, the alien device is snatching people and — for unknown reasons — transporting them into worlds of mythology. Dr Lukacs is one of the victims. Granted, he's an expert on mythology. But myths are not something he'd thought to encounter personally... moreAn alien pyramid has appeared on Earth, squatting in the middle of Chicago. It is growing, destroying the city as it does — and nothing seems able to stop it, not even the might of the US military. Somehow, the alien device is snatching people and — for unknown reasons — transporting them into worlds of mythology. Dr Lukacs is one of the victims. Granted, he's an expert on mythology. But myths are not something he'd thought to encounter personally. Or wanted to! Sure, he has a couple of tough paratroopers along with him, as well as a blonde Amazon biologist and a very capable maintenance mechanic. Unfortunately, modern weapons don't work, and the Greek gods are out to kill the heroes.Well, yes, they've got Medea and Arachne and the Sphinx on their side (both Sphinxes, actually — the Greek version as well as the Egyptian). And at least some of the Egyptian gods seem friendly.But that can be a very mixed blessing, to say the least. Oh, and whatever you do—don't mention dwarf-tossing. less

Alien Ragnarok!A mysterious pyramid appears in Chicago, oozing fantastic creatures and sucking humans into our own mythological past. It's an alien invasion from within!When a special forces team sent to capture an AWOL official gets into deep trouble with a certain one-eyed Norse god, redoubtable comparative mythologist Jerry Lukacs must rescue them, strike a deal with the droll and dangerous Loki, and risk bringing on Ragnarok itself to once again save human myth from alien domination... moreAlien Ragnarok!A mysterious pyramid appears in Chicago, oozing fantastic creatures and sucking humans into our own mythological past. It's an alien invasion from within!When a special forces team sent to capture an AWOL official gets into deep trouble with a certain one-eyed Norse god, redoubtable comparative mythologist Jerry Lukacs must rescue them, strike a deal with the droll and dangerous Loki, and risk bringing on Ragnarok itself to once again save human myth from alien domination.The rollicking sequel to New York Times best-seller Eric Flint and David Freers's action-packed romp through everything humankind holds sacred begun in the groundbreaking Pyramid Scheme. less