Philip José Farmer's World of Tiers series

Yesterday I wrote about Philip José Farmer's Riverworld series. Equally, and perhaps even more exciting is his World of Tiers series, beginning with the Maker of Universes and followed by The Gates of Creation and A Private Cosmos.

The first novel (published in 1965) starts out with a bang. An old man named Robert Wolff hears a trumpet call coming from a closet. He thinks he is going senile, but the closet is a portal to another world, filled with Edgar Rice Burroughs style adventures. The first three books have plenty of great death traps, puzzles, and surprises that I didn't see coming (I was 14 or 15 when I read them for the first time.)

This collection has the first three books. The other books in the series are not very good. $11.67 on Amazon