Römerkastell Caelius Mons, Roman fort archaeological site in Kellmünz, Germany.

Romerkastell Caelius Mons is an archaeological site with preserved foundations of walls and towers from the late Roman period. The excavated remains reveal the typical layout of a Roman cohort fort, including a reconstructed tower that stands on the grounds.

The Romans built this fortress in the late 3rd century to defend the Danube-Iller-Rhine Limes frontier against Germanic and Alamannic incursions. The fort was constructed during a period of heightened pressure along this critical border region.

The fort's name Caelius Mons derives from Caelius, one of Rome's seven hills; the Notitia dignitatum records it as Caelio, and the modern place name Kellmünz may come from it. A hall-like building inside the fort served in the first half of the 4th century for state representation, receiving Alamannic embassies and holding court sessions.

The fort's remains lie in the western part of Kellmünz's village centre and are almost completely built over; only the foundations of the wall and some towers in the west and north survive. St. Martin's church stands on the former south-east corner. The site is part of the Archäologischer Park Kellmünz.

The fort's name comes from the Notitia dignitatum, which records it as Caelio, derived from Caelius, one of Rome's seven hills. The modern place name Kellmünz may also trace back to this Roman name.