Gibralter
The Strait of Gibraltar and the Suez Canal
Tangier, is a Moroccan seaport that is located on the strait of Gibraltar.
The least distance is across the Strait of Gibraltar.
The Strait of Gibralter is a famous place.
It empties into the Atlantic Ocean through the Strait of Gibralter, not into any country.
Spain and morrocco
The distance between Portugal and Morocco is approximately 560 kilometers (350 miles) across the Strait of Gibraltar.
It's Portugal
25 miles
I eyeballed the Med and decided that the Strait of Gibraltar was the spot where Europe was closest to Africa. At it's narrowest point the Strait is only about 16 km. wide if you simply measure the distance using the scale on the Google Map of the Strait. However, if you do a search on the Strait of Gibraltar you will discover that the actual distance is only 14.3 km. That appears to be the most accurate answer. See the related link.
The Pillars of Hercules refers to two rock promontories located where the Mediterranean and the Atlantic meet. The one on the North side is the Rock of Gibralter (in Gibralter), the one on the South is Jebel Musa (in Morocco).