From the Greek words 'amphi', on both sides, + 'theatron', the ancient Roman building type used for gladiatorial contests and other entertainments.
One of the best preserved examples of this type is the Flavian amphitheater or 'Colosseum'; an enormous 525'x450' wedge shaped oval, four levels high, seating 50,000 people on raised tiers, each with a good view of the center of the theater.

The ancient Roman commemorative monument in the shape of an arch.
The bas relief sculpture on the Arch of Constantine depicts his victory over his rival Maxentius, in which he becomes the absolute monarch of the Roman empire.

Atrium In an ancient Roman house, the central courtyard. Today, an atrium may be covered with glass rather than open to the sky.

The system of the ancient Romans for the placement of buildings and roads that uses parallel and perpendicular lines in an even spacing. Also called a grid pattern.

An engineering structure designed to bring huge quantities of pure water into the city. The u-shaped stone channel that carries the water is at the top of the arcuated structure that is used to span valleys between the source and the city.

In ancient Roman architecture, a large meeting hall most often used for the law courts. The basilica could also contain the stock exchange, business and offices administrative offices, and therefore was a physical link between law and business.
There are two very different formal expressions of the basilica, illustrated by the earlier Basilica Ulpia or Trajan's Basilica, and the later Basilica of Maxentius and Constantine.
The roof of the trabeated structural system in Trajan's Basilica is supported by many interior columns thus breaking the large space (182' x @450') into smaller sections.
The Basilica of Constantine had an enormous arcuated system (200'x300') of barrel and groin vaults. It carried the thrust of the vaults on piers, and relied on massive buttressing.

In ancient Roman architecture, this structure combined public baths, gymnasium, excercise yards, stadia, shops, libraries and meeting rooms. Natural light entered through clerestory windows in the ends of the barrel vaulted roofs. It was a masterpiece of engineering providing and disposing of clean water of various temperatures for up to 1600 bathers on a daily basis.

The Imperial Roman military camp, an extremely rigid and orderly square, divided into four quadrants by the primary roads and oriented to the cardinal directions. This form, which was originally used for the temporary camps of the soldiers in new colonies, became the built form of those cities.

In ancient Roman architecture, the structure built for the running and viewing of chariot races. The Circus Maximus, or Domition's Circus, in Rome seated 200,000 people. The space of this circus survives today as the Piazza Navona.

The freestanding column in ancient Roman architecture has a commemoritive function.
The Column of Trajan, built by the Roman Emperor Trajan, records Trajan's successful military campaigns in which he extended the Empire into what is now Hungary and Romania.

The ancient Roman word for house. Examples from Pompeii or Ercolano indicate a single story house with a central atrium or courtyard which was a garden. The larger of these houses may also be referred to as villas.

The open air urban space(s) in ancient Roman cities, generally rectangular in shape, defined by the porticoes and civic buildings at its perimiter, and used for marketplace and public interaction, particularly 'civic discussion'. The temple stood prominently at one end of the forum.

The building type from the ancient Roman society made up of a block with shops and light industry at the ground level and apartments above. These structures ranged in height from four to seven stories.

In ancient Roman cities, the public market was located on or adjacent to the forum and varied somewhat in shape. See Trajan's market, and the market in Pompeii.

The domestic building for Roman emperors, at the scale of a small city.
In Diocletian's palace in Split or Spalato, Yugoslavia, the form is based on a Roman 'castrum' or camp, i.e., it is square in plan and divided into four quadrants. Unlike the castrum, it was solidly built and employed sumptuous materials. It was 300 by 400 meters square or @984' x 1312'.

In Imperial Rome, the structure used for religious ritual of the priests, and either rectangular or round in plan. The earlier rectangular plan temples have bearing walls. The round Pantheon employs an arcuated system for enclosing the space. Both forms stood on podiums and were meant to be approached only from the front.

The ancient Roman building type used for dramatic performance or entertainment. Unlike the Greek theater, the building is free standing, the wall behind the stage is much higher and the seating area may be covered.

A country house for the ancient Romans, typically of one story with a central atrium or courtyard. This term is also applied to many of the houses along the seawall in Pompeii and Ercolano (Herculaneum) because these cities were seaside resorts for wealthy Romans.