The fort was located on a low hill, beyond which a long promontory then projected north-eastwards into the sea and formed the north-eastern extremity of mainland Kent: thus it offered observation on all sides, including both the Thames Estuary and the sea lane later known as the Wantsum Channel, which lay between it and the Isle of Thanet.; . It was probably built by soldiers of the Cohors I Baetasiorum, originally from Lower Germany, who had previously served at the Roman fort of Alauna at Maryport in Cumbria at least until the early 180s, since tiles recovered from the fort are stamped "CIB". The Notitia Dignitatum, a Roman administrative document from the early 5th century, also records the presence of the Cohors I Baetasiorum at Reculver, then known as Regulbium.; . There must also have been a harbour nearby in Roman times, and, though this has not yet been found, it was probably near to the fort's southern or eastern side.; .
