Algeria is the largest country crossed by the Prime Meridian, the line of longitude defined as 0 degrees.
The Prime Meridian passes through western Algeria, crossing part of the Sahara before continuing south through Mali, Burkina Faso, Togo, and Ghana. It also passes through parts of Europe, including the United Kingdom, France, and Spain, before reaching Africa.
A common mistake is to assume the line passes through Greenwich alone. Greenwich in London is the historic reference location, but the meridian continues north and south around the globe. Algeria’s large desert territory makes it the biggest country on its route.
This distinction is about total country area, not the length of meridian crossing or the size of the capital. Algeria is also Africa’s largest country, so its continental area record and its Prime Meridian record come from the same extensive Saharan territory.