like most of these prehistoric monuments. They are
situated in an inhabited valley, and the ruins consist of five main
groups, some of which are exceedingly well preserved. Indeed, whilst
the ruins of Mitla are by no means so extensive as others described,
they are in the best state of preservation of any in the country. And
this is due both to their method of construction and to their
environment; for, unlike the low, tropical regions of Chiapas and
Yucatan, this district is at a considerable altitude above sea-level.
The great "palaces" or halls which these groups form, occupy an area of
about 1,800 feet from north to south, by 1,200 feet from east to west.
The principal groups are known as the "Hall of the Monoliths or
Columns," the "Catholic group," and the "Arroyo group." Like some of
the pyramids throughout Mexico, these are oriented, in this case the
variation being but a few degrees from the cardinal points of the
compass. The remarkable Hall of the Monoliths is a building some 125
feet long by 25 feet wide, with a row of great stone columns running
down the centre. These columns are cut from a single piece of trachyte,
15 feet in height, and 3 feet in diameter at the base, tapering
somewhat upwards, but of almost cylindrical form, without pedestal or
capital. Whilst these columns are intact, the roof, which was doubtless
supported on beams resting on the column, is gone. The weight of these
monoliths is calculated at five or six tons, and they were cut from
quarries in the trachyte rock of the mountains some five miles away,
and more than 1,000 feet above the site of Mitla. In this quarry
half-cut blocks for columns and lintels are still in place. Food for
thought, even for the modern engineer, is this work.

[Illustration: PREHISTORIC MEXICO: RUINS OF MITLA; HALL OF THE
MONOLITHS OR COLUMNS.]

But the monolithic columns here are by no means the only remarkable
features of the masonry of Mitla. The interior and exterior of these
great halls are carved with a beautifully executed geometrical
design--the Greek pattern enclosed in a quadrilateral, the blocks upon
which they are cut being exactly fitted and adjusted in their places
with scarcely visible joints. Indeed, at Mitla, as in other places in
the Americas--Huanuco[9] and Cuzco, in Peru, for example--it seems to
have been deemed an essential and peculiar art to adjust great blocks
of stone with so great a nicety that no mortar was necessary and the
joints