lla called the opisthodomus or back
temple. The front columns at either end are spanned by horizontal beams
that uphold a sloping gable called a pediment, the flat, three-cornered
surface of which is generally adorned with sculpture in bas-relief, and
along the side-columns is placed what is known as the entablature, that
consists of three parts, the architrave resting on the capitals of the
columns, the frieze above it and the cornice, the last of which
sustains the flat roof, usually covered with tiles or marble copies of
tiles.

[Illustration: The Parthenon]

Greek architecture is generally divided into three groups or orders: the
Doric, Ionic, and Corinthian, each of which, though the buildings
belonging to them resemble each other in general plan, is distinguished
by certain peculiarities of the columns and entablatures. The Doric was
the earliest to be employed, but the Ionic, that early succeeded it, was
long used simultaneously with it, sometimes even in the same building,
whilst the Corinthian did not come into use until considerably later.

[Illustration: Metope from the Parthenon]

In the Doric order the column has no separate base, but rises direct
from the top step of the platform on which the building it belongs to
stands. It is of massive form and has what is known as an entasis or
slightly convex surface, it is generally fluted, that is to say, cut
into parallel perpendicular channels, several rings called annulets
connecting it with the capital, which consists of an echinus or rounded
moulding and an abacus or unrounded slab resting on the echinus. The
Doric entablature is equally simple, the architrave being perfectly
plain, whilst the frieze is adorned with triglyphs or three upright
projections with grooves between them, set at equal distances from each
other, the spaces separating them, known as metopes, being as a rule
enriched with fine sculptures of figure subjects. The frieze is
connected with the cornice by narrow bands called mutules resting on the
triglyphs and metopes, and the cornice itself has a plain lower band
known as the corona, surmounted by more or less decorated courses of
stone or marble.

[Illustration: Portion of Frieze of Parthenon]

[Illustration: Portion of Frieze of Parthenon]

[Illustration: Ionic Capital]

The Ionic and Corinthian orders are alike characterised by lightness and
grace rather than massiveness and simplicity. In both, the columns,
instead of rising d