Trantor is the planet that serves as the capital of the Galactic Empire in Isaac Asimov’s Foundation series. It is the Empire’s administrative centre and the seat of imperial power for much of the saga.
Asimov portrays Trantor as an almost entirely urbanized world covered by metal domes and immense city infrastructure. Its population depends heavily on imported food, making the planet both the dazzling centre of galactic civilization and a symbol of the Empire’s vulnerability.
Trantor’s importance changes after the Great Sack, when invading forces devastate the imperial capital. The event marks a major stage in the Empire’s decline and helps expose how fragile its centralized political system has become. The planet later remains significant through locations such as the Imperial Library and Streeling University.
The other options belong to different parts of the Foundation setting. Terminus becomes the capital of the First Foundation, Anacreon is one of the nearby breakaway kingdoms, and Helicon is associated with Hari Seldon rather than the imperial capital.