practicable hill, nor, where necessary, did it shrink from cutting
through a rock, say to the depth of sixty feet or so. It did not avoid
a river, but bridged it with a solid structure such as often remains
in use till this day. If it met with a marsh, wooden piles were driven
in and the road-bed laid upon them. When it came to a deep narrow
valley it built a viaduct on arches.

[Illustration: FIG. 1.--THE PONT DU GARD (AQUEDUCT AND BRIDGE).]

The road so laid was meant for permanence. A width of ground was
carefully prepared, trenches were dug at the sides, three different
layers of road material were deposited, with sufficient upward curve
to throw off the water, and then the whole was paved with
closely-fitting many-cornered blocks of stone. In the chief instances
there were sidewalks covered with some kind of gravel. The width was
not great, but might be anything between ten and fifteen feet. Along
such roads the Roman armies marched to their camps, along them the
government despatches were carried by the imperial post, and along
them were the most conveniently situated and commodious houses of
accommodation. For their construction a special grant might be made by
the Roman treasury--the cost being comparatively small, since the
work, when not performed by the soldiers, was done by convicts and
public slaves--and for their upkeep a rate was apparently levied by
the local corporations. Besides the paved roads there was, needless to
say, always a number of smaller roads, many of them mere strips of
four feet or so in width; there were also short-cuts, by-paths, and
ill-kept tracks of local and more or less fortuitous creation.

[Illustration: FIG. 2.--THE APPIAN WAY BY THE SO-CALLED TOMB OF
SENECA.]