The Colosseum is the biggest and stateliest monument of the Roman world. It's construction was begun by Vespasian in 72 A.D. and finished by his son Titus in 80 A.D..
The inside structure is built of tufo, masonry and concrete; the external of travertine; the steps are covered with marble. It has an elliptical form with an axes of 188 meters by of 156. The external walls, 57 meters tall, are formed by three orders of arcades, (Doric Ionic and Corinthian) surmounted by an upper part with elegant Corinthian pilasters and small rectangular windows. There can be seen the corbel that supported the poles used to extend the awning covering the whole amphitheatre. Picture below: Paul McCartney at Colosseum.

TEATRO DI MARCELLO :            

It's construction was initiated by Caesar and finished by Augustus (11-13 BC) who dedicated it to the memory of his nephew Marcus Claudius Marcellus. The inner structure in made of tufo or ( volcanic rock ) while the outer one is faced with travertine. Initially it was formed by two orders of 41 arcades, Doric and Ionic, and by a Corinthian upper part; it could hold 15,000 spectators. During the centuries has suffered many adaptations until the restoration in 1932 which, while still preserving the overhanging Palazzo Orsini, restored the remaining twelve outer arcades, assuring the stability with a series of arcades in peperino.

The main theaters in Rome today

ARGENTINA - TEATRO DI ROMA: LARGO ARGENTINA, 52 (ROMA CENTRO). TEL. 06 68804601

BELLI: PIAZZA S. APOLLONIA, 11 (ROMA TRASTEVERE). TEL. 06 5894875

DEI SATIRI: VIA DI GROTTAPINTA, 19 (ROMA CENTRO). TEL. 06 6871639

DEI SERVI: VIA DEL MORTARO, 22 (ROMA CENTRO). TEL. 06 6795130

DELLA COMETA: VIA DEL TEATRO DI MARCELLO, 4 (ROMA CENTRO). TEL. 06 6784380

DELLE MUSE: VIA FORLI', 43 (ROMA NOMENTANO). TEL. 06 44233649

DUE: VICOLO DUE MACELLI, 37 (ROMA CENTRO). TEL. 06 6788259

ELISEO: VIA NAZIONALE, 183 (ROMA CENTRO). TEL. 06 4882114

PICCOLO ELISEO: VIA NAZIONALE, 183 (ROMA CENTRO). TEL. 06 4885095

EUCLIDE: PIAZZA EUCLIDE, 34 A (ROMA PARIOLI). TEL. 06 8082511

FLAIANO: VIA S. STEFANO DEL CACCO, 15 (ROMA CENTRO). TEL. 06 6796496

GHIONE: VIA DELLE FORNACI, 37 (ROMA AURELIO). TEL. 06 6372294

GRECO: VIA R. LEONCAVALLO, 10/16 (ROMA SALARIO). TEL. 06 8607513

MANZONI: VIA MONTE ZEBIO, 14 (ROMA PRATI). TEL. 06 3223634

OLIMPICO: PIAZZA GENTILE DA FABRIANO, 17 (ROMA FLAMINIO). TEL. 06 3265991

TEATRO ORIONE: VIA TORTONA, 7 (ROMA APPIO). TEL. 06 77206960

PARIOLI: VIA G. BORSI, 20 (ROMA PARIOLI). TEL. 06 8088299

PRATI: VIA DEGLI SCIPIONI, 98 (ROMA PRATI). TEL. 06 39740503

QUIRINO ETI: VIA M. MINGHETTI, 1 (ROMA CENTRO). TEL. 06 6794585

ROSSINI: PIAZZA S. CHIARA, 14 (ROMA CENTRO). TEL. 06 68802770

SALA UMBERTO: VIA DELLA MERCEDE, 50 (ROMA CENTRO). TEL. 06 6794753

TEATRO MOLIERE: VIA PODGORA, 1 (PIAZZA MAZZINI ROMA PRATI). TEL. 06 3223432

SISTINA: VIA SISTINA, 129 (ROMA CENTRO). TEL. 06 4200711

VALLE ETI: VIA DEL TEATRO VALLE, 23 (ROMA CENTRO). TEL. 06 68803794

IL VASCELLO: VIA G. CARINI, 72 (ROMA MONTEVERDE). TEL. 06 5881021

VITTORIA: PIAZZA S. MARIA LIBERATRICE, 8 (ROMA TESTACCIO). TEL. 06 5740598