Abydos Temple
Abydos was one of the most important religious sites to ancient Egyptians. Much like modern Muslims hope to complete a pilgrimage to Mecca at least once in their lifetime, ancient Egyptians would have hopes to visit Abydos, which for them was strongly associated with the entrance into the afterlife.
Since Abydos is more difficult to reach than many sites, it is not very heavily visited. Occasionally tour buses come from the beach resorts or with loads of cruise ship passengers from the Red Sea, but it you time your visit well, you might find yourself with the temple complex to yourself.
Abydos is easily included in a day trip from Luxor along with a visit to Dendara, another impressive, but lightly visited site