Taken from wikipedia,
Gebel el-Silsila is 65 km north of Aswan, where the cliffs on both sides of the Nile narrow. The name Kheny (or sometimes Khenu) means "The Place of Rowing". It was used as a quarry site from at least the 18th Dynasty to Greco-Roman times.http://en.wikipedia.org/wiki/Talatat
This is the pylon in Edfu Temple most Temples have two some have three,
also a few of the pylons have been demolished some say the temple of Pharaoh Amenhotep III.
was destroyed by the Pharaos others say by earthquake. most of the stones from the Gebel el-Silsila where used to construct other buildings. but originaly sat inside these huge pylons the smallest is 100 ft high