0 B.C.) is the likeliest date; all that is
actually certain is that the foundation was made before the end of the
first century A.D. This 'colonia', like others, was laid out in
chess-board fashion, and vestiges of its streets survive in the Centro
which forms the heart of the present town. The Centro of Florence, as
we see it to-day, is very modern. It was, indeed, laid out a
generation ago by Italian architects who designed the broad streets
crossing at right angles which form its characteristic. But this
'Haussmannization' revived, consciously or unconsciously, an old
arrangement. The plan of Florence in 1427 shows a group of twenty
unmistakable 'insulae', each of them about 1-1/8 acre in area, that
is, very similar in size to the 'insulae' of Turin. This group is
bounded by the modern streets Tornabuoni on the west, Porta Rossa on
the south, Calzaioli on the east, Teatina on the north; it covers a
rectangle of some 305 x 327 yds., not quite 21 acres.

[81] On Roman and early mediaeval Florence see Villani, _Cronica_
(written about 1345, published 1845), i. 61, 89, 120; R.
Davidsohn, _Geschichte von Florenz_ and _Forschungen_ (Berlin,
1886); L.A. Milani, _Notizie degli Scavi_, 1887, p. 129; plan of
the Centro in 1427 by Comm. Guido Carocci, _Studi storici sul
Centro di Firenze_ (Florence, 1889); _Monumenti antichi_, vi. 15.
Nissen _(Ital. Landeskunde_, ii. 296) fixes its area at 400 x 600
m., about 58 acres.

[Illustration: FIG. 17A. FLORENCE, SINCE THE REBUILDING OF THE
CENTRAL PORTION (Centro shaded).]

[Illustration: FIG. 17B. FLORENCE ABOUT 1795, FROM L. BARDI.
The chief streets which seem to have preserved Roman lines are marked
in black.]

The original Roman town presumably extended beyond these narrow
limits. But it is not easy to fix its area, nor are unmistakable
'insulae' to be detected outside them. On the west the Via Tornabuoni
seems to have marked the Roman limit, as it does to-day. On the north,
a probable line is given by the gateway, Por Episcopi, which once
spanned the passage--now an open space--on the east side of the
Archbishop's Palace (plan 17 B). That gateway stood between the Via
Teatina and the next street to the north, the Via dei Cerretani, and
the Roman north wall and ditch apparently ran along the intervals
between these two modern streets--as indeed the lines of certain
mediaeval lanes suggest. On the east the 'colonia' is supposed to have
stretched