emporium

Borrowed from Latin emporium (“trading station; business district in a city; market town”), from Ancient Greek ἐμπόριον (empórion, “factory, trading station; market”), from ἔμπορος (émporos, “merchant, trader; traveller”) + -ιον (-ion, suffix forming nouns). ἔμπορος is derived from ἐμ- (em-) (variant of ἐν- (en-, “in; within”)) + πόρος (póros, “journey; passageway”) (ultimately from Proto-Indo-European *per- (“to go through; to carry forth”)), modelled after ἐν πόρῳ (en pórōi, “at sea; en route”).

Sense 4 (“the brain”) alludes to the organ as the place where many nerves or nerve impulses meet.

Not related to English empire.