* The Greenwich Observatory in Greenwich, England. This is where the meridian was originally defined in the late 19th century.

* The Atlantic Ocean. It crosses the Atlantic Ocean both north and south of the Greenwich Observatory.

* The African continent. It crosses through several African countries, including Ghana, Togo, Benin, Nigeria, Cameroon, Gabon, the Democratic Republic of Congo, and Angola.

* The Southern Ocean. It crosses the Southern Ocean near the South Pole.

* The Arctic Ocean. It crosses the Arctic Ocean near the North Pole.

It's important to note that the Prime Meridian is an imaginary line, not a physical one. It's a line of longitude that defines 0 degrees longitude and acts as the reference point for measuring longitude around the world.