Opposite Earth
The North American and South American continents are offset so that the east coast of North America more or less lines up with the west coast of South America. This being the case, one might think of the "center" of the Western Hemisphere as being the location where the equator intersects this line, that is, the point along the western coast of South America where the equator crosses. This would be a point approximately halfway between Portoviejo and Esmereldas along the northern coast of Ecuador. Where would the point on the earth be located that is exactly opposite this point (i.e., the "middle" of the Eastern Hemisphere)?