of the old trackways of England, that the wild path
which the earliest men used, when it approaches a river, seeks out a
spur of higher and drier land, and if possible one directly facing
another similar spur upon the far side of the water. It is a feature
which the present writer continually observed in the exploration of
the old British trackway between Winchester and Canterbury; it is
similarly observable in the presumably British track between Chester
and Manchester; and it is the feature which determined the site of
London Bridge.

From the sea for sixty miles is a succession of what was once
entirely, and is now still in great part, marshy land; or at least if
there are no marshes upon one bank there will be marshes upon the
other. In the rare places down stream where there is a fairly rapid
rise upon either side of the river the stream is far too wide for
bridging; and these marshes were to be found right up the valley until
one struck the gravel at Chelsea: even here there were bad marshes on
the farther shore.

There is in the whole or the upper stretch of the tidal water but one
place where a bluff of high and dry land faces, not indeed land
equally dry immediately upon the farther bank, but at least a spur of
dry land which approaches fairly near to the main stream. If the
modern contour lines be taken and laid out upon a map of London this
spur will be found to project from Southwark northward directly
towards the river, and immediately opposite it is the dry hill,
surrounded upon three sides by river or by marsh, upon which grew up
the settlement of London. Here, then, the first crossing of the Thames
was certain to be made.

It is not known whether a permanent bridge existed before the Roman
Conquest. It may be urged in favour of the negative argument that
Caesar had no knowledge of such a bridge, or at least did not march
towards it, but crossed the river with difficulty in the higher
reaches by a ford. And it may also be urged that a bridge across the
Rhine was equally unknown in that time. But, the bridge once
established, it could not fail to become the main point of convergence
for the commerce of Southern England, and indeed for much of that
which proceeded from the North upon its way to the Continent. Such an
obstacle would oppose itself to every invasion, and did, in fact,
oppose itself to more than one historical invasion from the North Sea.
It would further prevent sea-going vessels whose ma