have appeared insuperable. The first aqueduct was erected by Ap'pius
Clo'dius, the censor, four hundred years after the foundation
of the city; but under the emperors there were not less than twenty of
these useful structures, and such was the supply of water, that rivers
seemed to flow through the streets and sewers. Even now, though only
three of the aqueducts remain, such are their dimensions that no city
in Europe has a greater abundance of wholesome water than Rome.

21. The Cloa'cæ, or common sewers, attracted the wonder of the
ancients themselves; the largest was completed by Tarquin the Proud.
The innermost vault of this astonishing structure forms a semicircle
eighteen Roman palms wide, and as many high: this is inclosed in a
second vault, and that again in a third, all formed of hewn blocks of
pepenno, fixed together without cement. So extensive were these
channels, that in the reign of Augustus the city was subterraneously
navigable.

22. The public roads were little inferior to the aqueducts and Cloa'cæ
in utility and costliness; the chief was the Appian road from Rome to
Brundu'sium; it extended three hundred and fifty miles, and was paved
with huge squares through its entire length. After the lapse of
nineteen centuries many parts of it are still as perfect as when it
was first made.

23. The Appian road passed through the following towns; Ari'cia,
Fo'rum Ap'pii, An'xur or Terraci'na, Fun'di, Mintur'næ, Sinue'ssa,
Cap'ua, Can'dium, Beneven'tum, Equotu'ticum, Herdo'nia, Canu'sium,
Ba'rium, and Brundu'sium. Between Fo'rum Ap'pii and Terraci'na lie the
celebrated Pomptine marshes, formed by the overflowing of some small
streams. In the flourishing ages of Roman history these pestilential