The Western Hemisphere is the half of the planet Earth that lies west of the Prime Meridian (which crosses Greenwich, London, England) and east of the 180th meridian. The other half is called the Eastern Hemisphere. Politically, the term Western Hemisphere is often used as a metonymy for the Americas, even though geographically the hemisphere also includes parts of other continents. Geography The Western Hemisphere consists of the Americas, excluding some of the Aleutian Islands to the southwest of the Alaskan mainland; the westernmost portion of Europe, both mainland and islands; the westernmost portion of Africa, both mainland and islands; the extreme eastern tip of the Russian mainland and islands (North Asia); numerous territories in Oceania; and a large portion of Antarctica. The center of the Western Hemisphere is located in the Pacific Ocean at the intersection of the 90th meridian west and the Equator, among the Galápagos Islands. The nearest land is Genovesa Island at . The highest mountain in the Western Hemisphere is Aconcagua in the Andes of Argentina at . The tallest freestanding structure in the Western Hemisphere is the CN Tower in Toronto at and the tallest building in the Western Hemisphere is One World Trade Center in New York City at . Alternative definitions In an attempt to match the Western Hemisphere more closely with the Americas, some sources use the 20th meridian west and the diametrically opposed 160th meridian east to define the hemisphere. This definition excludes all of the European and African mainlands, but still includes some islands associated with these continents, more of eastern Russia and Oceania, and part of Antarctica. It includes all islands of Alaska, but excludes a small portion of northeast Greenland. There is no hemisphere that includes all of the Americas while excluding all land outside of it, regardless of the meridians or points chosen to define it. Sovereign states in both hemispheres Below is a list of the sovereign states in both the Western and Eastern hemispheres on the IERS Reference Meridian, in order from north to south: Denmark, due to the entirety of Greenland and the Faroe Islands. Denmark proper lies entirely within the Eastern Hemisphere. Norway, due only to Jan Mayen. Mainland Norway, Svalbard and Bouvet Island lie entirely within the Eastern Hemisphere. United Kingdom, passing through Greenwich, London. Most of the country lies within the Western Hemisphere. The Netherlands has overseas islands that lie