Luxor is one of the main cities in southern Egypt and it was the site of the Ancient Egyptian city of Thebes. Across the River Nile lie the most famous temples, tombs and other monuments, including the Valley of the Kings and Valley of the Queens.
It was the Ancient Greeks who called the city Thebes. The Ancient Egyptians knew it as "Waset". It was the main place of worship for the god Re (Amun).
The ancient city became important with the 11th Dynasty of kings. The famous kings of the New Kingdom (including Ramesses II) brought wealth to the city and increased the size of the temples as they conquered more and more land and made it part of the Egyptian empire. Between the 18th and 20th dynasties the city was the capital of Ancient Egypt.
Each region of Egypt had it own patron god or goddess. The main god of Thebes was Amun, who was worshipped together with his wife, the Goddess Mut, and their son Khonsu, the God of the moon. As Thebes became the most important city in Egypt, the local god Amun rose in importance and became linked to the sun god Ra. In this way the new 'king of gods', Amun-Ra, was created. It was to him that the great temple area at nearby Karnak was built.
Note that there are two temple areas at Thebes. One is inside the city of Luxor. It is the one with the seated statues of Ramesses, one with a fallen head. The other, bigger, temple at Karnak is the one with the vast hall of columns (Hypostyle Hall). Both are close to the river, Karnak being to the north (downriver) of Luxor.