 Complete the following phrase:  A dendrochronological dating of the wood enables us to say that the fort was built after the state visit of Caligula to Germania Inferior in AD 40-41. The wooden building was meant to protect the limes; the Roman border consisting of the Rijn. Caligula built this fort with the idea of crossing over to Great Britain; this was not accomplished during his reign, although his successor Claudius succeeded. The building was an isolated outpost, few colonies were located nearby. The complex was exclusively made of wood. It had wooden outer walls and wooden watchtowers. Outside the walls canals were dug. This wall was approximately a hundred and twenty meters long and eighty meters wide. During the 