Babel Tower

Babel Tower is one of a series of commercial complexes on the outskirts of the Tokyo Settlement, administrated by organized criminal elements as a casino wherein human trade and other illegal practices are rampant.

Background
Lelouch first appears in this building to gamble against the Black King, whom he defeats at chess. After the Black Knights infiltrate it to retrieve Lelouch, he recovers his memories of being Zero and directs the Black Knights to destroy it, simultaneously killing the current Viceroy Calares and making a direct path to the Chinese Consulate.