Ovid's Metamorphoses.
It's kind of a history of the world, including a big flood, and then a series of mythological stories, like Jupiter and Juno's constant marital problems due to his incessant infidelities and the havoc this wreaks on mortals and other demigods. Poor Io, the nymph, that got turned into a cow, and Argus, the hundred eyed sentinel who had to watch over her. Neither one had a great time of it. Then there's the scallywag mortal child of Apollo (Phoebus), Phaeton, who asks Dad if he can borrow the car. Things go downhill from there. It's a series of short episodes -- so rather easy and entertaining. Many myths that I'd heard in passing are laid out in greater detail here, so it's pretty fun.
