Hadrian's Wall

The original concept of the wall didn't include forts, but these were soon added. Early forts such as Cilurnum, occupied by 124 AD, straddled the wall and demolished earlier work; later structures (e.g., Housesteads) were set back. This fort guarded the bridge over the River North Tyne, and was a base for cavalry. So raiders from the north could expect not only pursuit over many miles, but destruction of any village that sheltered them or that might hypothetically do so in future. The troops of all the forts were auxiliaries not Roman citizens, following the strategy of imperial dominoes: those from Bosnia and from the Upper Rhineland were stationed here not long after their own homelands had been subjugated. They formed the 500-strong ala Augusta ob virtutem appellata, "the cavalry regiment called Augusta for its valor", and worshipped (or else!) the military goddess Disciplina. It's not clear how the fort was used when the frontier advanced to the Antonine Wall, but from 180 AD to the end of the Roman period it was garrisoned by the "Second Asturians" from northern Spain. A civilian town grew up on its south side but hasn't been excavated. The fort and wall were disused from the 5th century and the Saxons took the stone for building, while fields engulfed the site. From 1796 Nathaniel Clayton had it levelled, burying the site to create a more pleasing landscape, but his son John Clayton reversed this and began the preservation of the entire wall.

This is the most substantial Roman fort not just on the wall but in Britain, and one of the best-preserved in Europe. It's referred to as an "auxiliary fort" but it was the 800 troops who were auxiliary, the Tungrians from Belgium and cuneus Frisiorum and numerus Hnaudifridi from Frisia; but all of these forts were as substantial as they needed to be to protect an empire. The north flank of Vercovicium was on the wall but it didn't straddle, perhaps due to unstable ground just north. It also lacked a running water supply, but collected enough from the lashing rain. The ruins include the barracks, bathhouse, Turret 36B, the adjacent civilian settlement, and the wall itself. In the 17th century a band of rustlers lived here and penned their stolen herds within; their farmhouse has been dismantled to uncover the present site. It's owned by National Trust and managed by English Heritage.

Vindolanda was built in 85 AD so it pre-dates the wall and is two miles south. It was a fort, civilian settlement and caravanserai along Stanegate, the road between the Tyne and Solway. The road was designed for heavy carts so it was broad, paved, and wound up gradients instead of marching straight. Other forts lined Stanegate but they were more like secure truck parks, keeping out thieves but not mob-handed raids — that was the wall's job. The boggy soil has preserved many artefacts, such as sandals, wool-spinners' whorls, combs, a wooden toilet seat, a Christian chalice, and boxing gloves that appear sporting not gladiatorial. Writing tablets inscribed in ink (not by stylus) contain a birthday party invitation from 100 AD: most of these tablets are in the British Museum in London but a selection are here. In the gardens by the museum are reconstructions of Roman buildings. They also run the Roman Army Museum 7 miles west at Walltown: ticket prices are for both (valid for one year) though you can buy separately.

This large fort overlooks a spur in the River Irthing. The wall this far west was only turf, then circa 130 AD the stone wall was built 50 yards north. It's the only fort to show clear evidence of post-Roman occupation, probably because of its lowland setting on a transport route, and this culminated in the 19th century farmhouse now within the site. You can park nearby but a pleasant stroll from Gilsland follows the wall past Milecastle 48 (Poltross Burn), Turret 48B, over a footbridge near the abutments of the Roman river bridge, then Milecastle 49 (Harrows Scar). A little way past the fort is Turret 49B. The site is managed by English Heritage.