Recently I have seen photographs of El Fuerte after restauration by UNESCO. Great work! Me and my wife visited El Fuerte in 1998.
In the past years I have done some research on the meaning of 'El Cascabel':one of El Fuerte's most significant features.
The 263 diamantshaped curves on El Cascabel and the view direction of the two parallel shafts of El Cascabel ( azimuth 71"0')show the importance of Venus, the morningstar.
It was Garcilaso de la Vega in his ancient chronicles of Peru who mentioned this temple for the first time.
In his description he speaks about he stone images of two condors (cunturs) that could be found on this hill. One cuntur was depicted in flight 'as to swoop on it's pray' and one cuntur with 'it's back turned to the spectator as in shame'.
Both images still can be seen on El Fuerte although they haven't been published before and are also unknown by UNESCO.
Besides that one particular spot one El Fuerte should be protected very well because this spot marks the (unknown and not-published)images of the mythical Manco Ccapac and Mama Occlo and also the images of two Llamaheads (offers?).
The writings of Garcilaso de la Vega show us that El Fuerte was pretty famous in Cusco and he writes:
"the painting still existed in good condition in 1580. In 1592 I asked a creole priest who had come to Spain from Peru if he had seen it and what state it was in. He replied that it was very faint, and indeed scarcely perceptible at all, having been ruined by wheather and water and neglect for the preservation of such antiquities" (Garcilaso de la Vega, Chapter XXIII: a famous painting; the rewards given to the Inca allies)
I hope UNESCO will take care of these paintings now. I will reveal these places in personal communication with UNESCO.