Crystal Tokyo (クリスタル・トーキョー) was the new name given to Tokyo when Neo-Queen Serenity and King Endymion ascended the throne to rule over Earth in the 21st Century. It became not only the capital of Japan, but also of the entire Earth. It was a utopia, the epicentre of the new Silver Millennium, at the center of which stood the Crystal Palace.
In the anime, the city formed the shape of a five-pointed star when seen from above. The five locations which formed the points of that star were known as Crystal Points; various members of the Black Moon Clan tried to take contol of those points in the past on Earth in order to prevent Crystal Tokyo from existing in the future.