The ancient Greeks associated the entrance to Hades with a real-life location in ancient Greece. Where was this place?

Hermes relates how one day she is out picking flowers when Hades, god of the underworld, comes to the upper world and sees her. Hades is entranced and takes Persephone down to his underground ...

The Underworld is the realm of the dead ... When Heracles arrives at Hades’s palace, he convinces Hades to let him take ...