bstructure of stone, upon which was raised
a conical elevation. In the case of the Regulini Galeassi tomb there
were an inner and an outer tumulus, the latter of which covered
several small tombs, while the inner enclosed one only, which had
fortunately never been opened till it was lately discovered. This tomb
was vaulted on the horizontal system--that is to say, its vault was
not a true arch, but was formed of courses of masonry, each
overhanging the one below, as in the Treasury of Atreus, and it had a
curious recess in the roof, in which were found numerous interesting
examples of Etruscan pottery. It is, however, clear from the city
gates, sewers, aqueducts, &c., that the Etruscans were acquainted with
and extensively used the true radiating arch composed of wedge-shaped
stones (voussoirs), and that they constructed it with great care and
scientific skill. The gate at Perugia, and the Cloacae or Sewers at
Rome, constructed during the reign of the Tarquins,[19] at the
beginning of the sixth century B.C., are examples of the true arch,
and this makes it certain that it was from the Etruscans that the
Romans learned the arched construction which, when combined with the
trabeated or lintel mode of construction which they copied from the
Greeks, formed the chief characteristic of Roman architecture. The
Cloaca Maxima (Fig. 123), which is roofed over with three concentric
semicircular rings of large stones, still exists in many places with
not a stone displaced, as a proof of the skill of these early
builders. There are remains of an aqueduct at Tusculum which are
interesting from the fact of the horizontal being combined with the
true arch in its construction.

[Illustration: FIG. 123.--CLOACA MAXIMA.]

No Etruscan temples remain now, but we know from Vitruvius that they
consisted of three cells with one or more rows of columns in front,
the intercolumniation or interval between the columns being excessive.
The largest Etruscan temple of which any record remains was that of
Jupiter Capitolinus at Rome, which, under the Empire, became one of
the most splendid temples of antiquity. It was commenced by Tarquinius
Superbus, and is said to have derived its name from the fact of the
builders, when excavating the foundations, coming upon a freshly
bleeding head (_caput_), indicating that the place would eventually
become the chief city of the world. Another form of Etruscan temple is
described by Vitruvius, consisting of o