What was the Roman name for London?

The Roman name for London was Londinium. This name was used during the Roman occupation of Britain, which lasted from AD 43 to about AD 410. Londinium was established as a significant settlement due to its strategic location along the River Thames, which facilitated trade and military movement. Over time, it grew into the largest city in Roman Britain and became an important administrative and commercial center.

Each of the other names does not correspond to London in its historical context. Caesaropolis could suggest a city named after Julius Caesar, but there is no historical record of such a naming for London. Britannia is the Latin term for the entire island of Britain rather than a specific city. Romantropolis is not a recognized historical term and seems to be a fictional or incorrect creation. Therefore, Londinium is the only correct designation that reflects London's historical identity during the Roman era.