Mayapan, Mexico, satellite image. North is at top. The ruins of this city are at centre, surrounded by forest, and a road. Mayapan, built by the Mayan civilisation, reached its zenith around 1200. The largest pyramid is the Castle of Kukulkan, made as a smaller replica of the Castle of Chichen Itza. It is thought that numerous structures in the city were aligned so that sunlight shone on particular areas on important astronomical dates, such as the solstices and equinoxes. The Mayas had advanced astronomical knowledge and could predict solar and planetary events and created precise calendars. Image obtained by the Ikonos satellite on 19 September 2001.