Which modern city is located across the major waterway from the
southernmost of the Pillars of Hercules?

Hello lisaann,

The Pillars of Hercules are commonly thought to have been situated on
each side of the Strait of Gibraltar. They are usually identified with
the Rock of Gibraltar on the north side and Mount Hacho in Ceuta on
the south side. This would make the city of Gibraltar the modern city
located across the waterway, ie the Strait of Gibraltar, from the
southern pillar.

Definition of the Pillars of Hercules from the 2001 edition of the
Columbia Encyclopedia: http://www.bartleby.com/65/pi/PillarsH.html

A map of the area: http://earth.esa.int/ew/special_events/Gibraltar/

Search strategy: 1. "Pillars of Hercules"  2. "Strait of Gibraltar"
map