Amphitheater, Pozzuoli

 http://en.wikipedia.org/wiki/Flavian_Amphitheater_(Pozzuoli)

http://www.ulixes.it/english/e_pg02gfr14.html

It took me awhile to find this coluseum. In Pozzuoli, the archeological sites are mixed right into the city. 

 Begun 69-79AD. There are many great examples of Roman building techniques in this site.