Polygonal Tusculum ----
{ Veii ----
Opus quadratum. First period, { Gabii ----
squared edges { Palatine Hill 753 B.C.
{ Second Wall of Rome 746 B.C.
Second period, bevelled edges { Aventine Hill 600 B.C.
{ Ostia 600 B.C.
_PEPERINO OF THE REPUBLIC._
{ Tomb of Scipio 298 B.C.
Opus quadratum { Temple of Hope 240 B.C.
Opus incertum Temple of Cybele 191 B.C.
Opus incertum, polygonal Emporium 190 B.C.
Opus quadratum Tabularium 78 B.C.
_TRAVERTINE AND BRICK OF THE EMPIRE._
{ Tomb of Cecilia Metella 78 B.C.
{ Theatre of Marcellus 13 B.C.
Opus quadratum { Arch of Dolabella 10 A.D.
{ Colosseum 80 A.D.
{ Muro Morto 80 B.C.
{ Tomb of Augustus 10 B.C.
Opus reticulatum { Palatine Tiberius' House ----
{ Palatine Germanicus' House ----
{ Hadrian's Villa ----
{ Hadrian's Ostia ----
Opus lateritium--
{ Pantheon Augustus.
Bricks, 6 to foot { Prætorian Camp Tiberius.
{ Palace Caligula.
Bricks, 8 to foot Aqueduct Nero.
Bricks, 7 to foot Palace Domitian.
Bricks, 6 to foot Temple of Venus and Rome Hadrian.
Bricks, 7 to foot Nymphæum, on Palatine M. Aurelius.
{ Baths Caracalla.
{ Nymphæum Alexander
{ Severus.
Bricks, 5 to foot { Walls of Rome Aurelian.
{ Thermæ Diocletian.
{ Basilica Constantine.
Bricks and tufa { Circus of Maxentius 300 A.D.
{ House of Gregory 590 A.D.
Opera Saracenesca S. Sisto Vecchio 1200 A.D.
Opus Spicatum Herring-bone pavement.
Opus Signinum Cement for reservoirs, etc.
[Illustration: PLAN OF ANCIENT ROME]