At the very top of the temple complex is the Temple of the Smoking Mirror.  I liked being at the top of this temple.  That is all I recall about the experience.

According to the LONELY PLANET: Guide to Mexico, 9th Edition,  (2004), ISBN 1-74059-686-2, page 811, the ruler Zots-Choj built the Temple of the Smoking Mirror sometime after 842 A.D.  Zots-Choj extended the northeast side of the hill to make this temple higher and further north than all of the others to commemorate the 4th and final Sun and the direction North.