The Mantilis was one of the large city-starships of the Caeliar civilization, originally located on the planet Erigol.

In 2168, the Columbia MACOs revolted against their forced imprisonment on the planet, and sought to take over the Great Work apparatus at Mantilis to open a subspace tunnel back to Earth for the ship to pass through. As backup, the MACOs had planted explosives at Feiran, destroying it at a critical moment to further their cause.

Mantilis was one of the few city-ships to survive the extragalactic feedback pulse that destabilized the Great Work and destroyed the solar system. When it emerged from the other end, Columbia chief engineer Karl Graylock questioned the Caeliar Lerxst as to their status and new location. The scientist replied that millions of Caeliar had sacrificed themselves to allow the six Starfleet personnel and twelve Caeliar inside the chamber survive. He then explained that they were approximately 59,000 light-years from Earth and thousands of years into the past, ending up in 4527 BCE. (ST - Destiny novel: Gods of Night)

The Mantilis ended up crashing on a frozen continent on the planet of Arehaz. It was in the ruins of the city ship that the Borg were created when the last surviving Caeliar Sedín forcibly bonded with the last three surviving humans in order to survive. It is likely that much of Borg technology is derived from the remains of the Mantilis. (ST - Destiny novel: Lost Souls)

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