Castra Gelduba, Roman military fort in Krefeld, Germany

Castra Gelduba is the Roman fort site at Gellep-Stratum in Krefeld, on a flood-free rise of the Rhine's lower terrace about ten metres above the river. The earth-and-timber camp of the 1st century was rebuilt in stone by about 150 and later enclosed by a stone rampart with semicircular towers around 380. Nothing stands above ground today; the buried remains lie under the fields of the Gellep district.

The original wood-and-earth fort went through three building stages before being rebuilt in stone by about 150, when it was held by the Cohors II Varcinorum equitata. The Franks destroyed it after the revolt of Postumus in 259 and again in 275–276; under the Tetrarchy it was rebuilt with only a stone rampart and raised to a castrum in 295. Destroyed again by the Franks in 353–355, it was rebuilt by Valentinian I, and around 380 semicircular towers and new ditches were added. It remained a Roman fortress until at least the 5th century.

The site's name comes from an earlier Ubii settlement; the Mühlenbach stream nearby marked the boundary between the Cugerni to the north and the Ubii to the south. The cemetery stayed in use into the late 8th century, and from the mid-5th century graves take on a Merovingian character, with a tumulus raised over one richly furnished burial and other wealthy Franks buried around it.

Archaeological finds from the fort are displayed at the Museumszentrum Burg Linn, where weapons, coins, and military equipment tell the story of the site. The museum provides the best way to understand the artifacts, as the actual excavation site has limited visibility.

The cemetery was used from Nero's reign (AD 54–68) until the late 8th century, with over 6,000 graves excavated. In the 4th century grave orientation shifted from north–south to east–west and grave goods became rarer; by the mid-5th century burials take on a Merovingian character, and a tumulus was raised over one richly furnished grave on the western edge.