Housesteads, owned by the National Trust, but in the care of English Heritage, is the most complete example of a Roman fort to be seen in Britain. It was one of twelve permanent forts built by Emperor Hadrian in about AD 124 for the garrison of his complex new frontier, now known as Hadrian's Wall. This handbook guides visitors on a tour of the fort, describing it as it is and as it was built, and gives a brief history of the fort and Northern Britain under the Romans.