Another of Egypt’s tentative sites that blows many listed sites out of the water.  Abydos was a very important city and is ancient even for ancient Egypt.  It was buried under sand until about the 1800s, which means that it is very well preserved.  In particular, it is known for having preserved colorful paintings on the inside of the Temple of Seti I.

It and Dendara, another tentative list site, can easily be combined on a (long) day trip from Luxor. Both are worth visiting.