Alexandria serves as the capital of Cleopatra's kingdom in Assassin's Creed Origins.
Origins is set in Ptolemaic Egypt during the first century BCE. Alexandria was founded by Alexander the Great in 331 BCE and became a major center of Mediterranean trade, scholarship, and political power. In the game, it is one of the largest and most important urban locations.
The city includes fictionalized versions of famous landmarks such as the Great Library, the Pharos lighthouse, and the Serapeum. Bayek of Siwa visits Alexandria while investigating the forces threatening Egypt and later becomes connected with Cleopatra's political struggle against Ptolemy XIII.
Memphis was another major Egyptian city and appears prominently in the game, but it is not the kingdom's capital in this context. Siwa is Bayek's home region, and Thebes is an older historical center farther south. Alexandria is the specific answer because it was the Ptolemaic capital and a central setting in the story.