’Of course, the farther North you go the emptier are the roads.  At last you fetch clear of the forests and climb bare hills, where wolves howl in the ruins of our cities that have been.  No more pretty girls; no more jolly magistrates who knew your Father when he was young, and invite you to stay with them; no news at the temples and way-stations except bad news of wild beasts.  There’s where you meet hunters, and trappers for the Circuses, prodding along chained bears and muzzled wolves.  Your pony shies at them, and your men laugh.

’The houses change from gardened villas to shut forts with watch-towers of grey stone, and great stone-walled sheepfolds, guarded by armed Britons of the North Shore.  In the naked hills beyond the naked houses, where the shadows of the clouds play like cavalry charging, you see puffs of black smoke from the mines.  The hard road goes on and on—­and the wind sings through your helmet-plume—­past altars to Legions and Generals forgotten, and broken statues of Gods and Heroes, and thousands of graves where the mountain foxes and hares peep at you.  Red-hot in summer, freezing in winter, is that big, purple heather country of broken stone.

’Just when you think you are at the world’s end, you see a smoke from East to West as far as the eye can turn, and then, under it, also as far as the eye can stretch, houses and temples, shops and theatres, barracks and granaries, trickling along like dice behind—­always behind—­one long, low, rising and falling, and hiding and showing line of towers.  And that is the Wall!’

‘Ah!’ said the children, taking breath.

‘You may well,’ said Parnesius.  ’Old men who have followed the Eagles since boyhood say nothing in the Empire is more wonderful than first sight of the Wall!’

‘Is it just a Wall?  Like the one round the kitchen-garden?’ said Dan.

’No, no!  It is the Wall.  Along the top are towers with guard-houses, small towers, between.  Even on the narrowest part of it three men with shields can walk abreast, from guard-house to guard-house.  A little curtain wall, no higher than a man’s neck, runs along the top of the thick wall, so that from a distance you see the helmets of the sentries sliding back and forth like beads.  Thirty feet high is the Wall, and on the Picts’ side, the North, is a ditch, strewn with blades of old swords and spear-heads set in wood, and tyres of wheels joined by chains.  The Little People come there to steal iron for their arrow-heads.

’But the Wall itself is not more wonderful than the town behind it.  Long ago there were great ramparts and ditches on the South side, and no one was allowed to build there.  Now the ramparts are partly pulled down and built over, from end to end of the Wall; making a thin town eighty miles long.  Think of it!  One roaring, rioting, cock-fighting, wolf-baiting, horse-racing town, from Ituna on the West to Segedunum on the cold eastern beach!  On one side heather, woods and ruins where Picts hide, and on the other, a vast town—­long like a snake, and wicked like a snake.  Yes, a snake basking beside a warm wall!