Tulum was first mentioned by Juan Díaz, a member of Juan de Grijalva's Spanish expedition of 1518, the first Europeans to spot Tulum. The first detailed description of the ruins was published by John Lloyd Stephens and Frederick Catherwood in 1843 in the book "Incidents of Travel in Yucatan". As they arrived from the sea, Stephens and Catherwood first saw a tall building that impressed them greatly, most likely the great Castillo of the site. They made accurate maps of the site's walls, and Catherwood made sketches of the Castillo and several other buildings. Stephens and Catherwood also reported an early classic stele at the site, with an inscribed date of AD 564 (now in the British Museum's collection). This has been interpreted as meaning that the stele was likely built elsewhere and brought to Tulum to be reused.