While al-Qāhirah is the official name of the city, in local speech it is typically called simply by the name of the country, Mişr (Arabic, مصر) pronounced Maşr in the local dialect.

The name Al-Qahirah literally means "The Subduer," though it's often translated as "The Victorious." The origin of the name is said to come from the appearance of the planet Mars during the foundation of the city. The planet Mars, associated with destruction was called "Al Najm Al Qahir" in Arabic, from which the name of the city was derived. However the legacy of the name evolved into the title "Qahirat Al Adaa" meaning "subduer of the enemies". This title was given to the city as many armies were destroyed in attempts to invade Cairo or defeated elsewhere by troops sent from Cairo. (Mongols, Crusaders & Ottomans are examples.)

Cairo remained the central city of Egypt throughout the period of British rule and afterwards. The 20th century saw massive growth in the size of the city as peasants left the farmlands in pursuit of work in the factories and commerce of the metropolis. The city was especially burdened by refugees from the various wars with Israel: much of the population of the Sinai peninsula and the cities along the Suez Canal left for Cairo between 1967 and 1978.

Today Cairo is Africa's most populous city and the Arab world's cultural centre.

Since the 19th century Cairo has also become a center for tourism as people from around the world have come to see the monuments and artifacts of Ancient Egypt, especially the Pyramids. Laws against the export of these treasures has meant that the Egyptian Museum in Cairo is the only place in the world that many items can be seen.

Source: Wikipedia