The Colosseum used to be known as the Flavian Amphitheater and was built in the middle of a broad valley between the Palatine, the Caelian and the Esquiline hills.  It is a very imposing structure with its major axis of the elliptical plan is 188 meter long, its minor axis 156 meters; as for the walls, they rise 50 meters above ground! Begun by Vespasian shortly after 70 AD, it was opened by Titus 10 years later!

The amphitheatre was the site of ceremonies and games with the well known gladiators fights amongs themselves and with wild animals.  There were explanatory pannels depicting the amazing organisation required to host those "games", shwoing how animals were kept, where gladiators entered the forum etc...