was succeeded by his brother Cassivelaunus, in whose
time happened the invasion of the Romans under Julius Caesar. Troynovant,
or London, then became a Roman city. It was newly fortified by Helena,
mother of Constantine the Great.'

This is the legend invented or copied by Geoffrey of Monmouth, and
continued to be copied, and perhaps believed, almost to the present day.
Having paid this tribute to old tradition, let us relate the true early
history of the City, as it can be recovered from such documents as
remain, from discoveries made in excavation, from fragments of
architecture, and from the lie of the ground. The testimony derived
from the lie of the ground is more important than any other, for several
reasons. First, an historical document may be false, or inexact; for
instance, the invention of a Brutus, son of AEneas, is false and absurd
on the face of it. Or a document may be wrongly interpreted. Thus, a
fragment of architecture may through ignorance be ascribed to the Roman,
when it belongs to the Norman, period--one needs to be a profound
student of architecture before an opinion of value can be pronounced
upon the age of any monument: or it may be taken to mean something quite
apart from the truth, as if a bastion of the old Roman fort, such as has
been discovered on Cornhill, should be taken for part of the Roman wall.
But the lie of the ground cannot deceive, and, in competent hands,
cannot well be misunderstood. If we know the course of streams, the
height and position of hills, the run of valleys, the site of marshes,
the former extent of forests, the safety of harbours, the existence of
fords, we have in our hands a guide-book to history. We can then
understand why towns were built in certain positions, why trade sprang
up, why invading armies landed at certain places, what course was taken
by armies, and why battles have been fought on certain spots. For these
things are not the result of chance, they are necessitated by the
geographical position of the place, and by the lie of the ground. Why,
for instance, is Dover one of the oldest towns in the country? Because
it is the nearest landing ground for the continent, and because its hill
forms a natural fortress for protecting that landing ground. Why was
there a Roman station at Portsmouth? On account of the great and
landlocked harbour. Why is Durham an ancient city? Because the steep
hill made it almost impregnable. Why is Chester so called? Because it