Temple of the Initial Series, Tulum
On the right side of El Castillo is the Temple of the Initial Series. Here they found a stelae that was older than the city, and that's how the temple got it's name. Unfortunately you can not see this stelae as it is in the British Museum (of all places). Archeologist thinks that the stelae must have been brought to this place from another, earlier city, since it is older than the foundation of Tulum.