>> mirella serlorenzi (/ translated/ ): it was clearly a garden, because we found in the layers traces of the roots of the plants, and in this part here, the staircase connected the various levels of the garden. >> cooper: is it possible to walk on it? >> serlorenzi:/ assolutamente. >> cooper: yeah? excellent. this is what serlorenzi's team believes the area looked like during caligula's reign. we ended up talking for a long time on the garden steps. is it all right to sit down? >> serlorenzi: sit, okay. >> cooper: there was something about touching those old slabs of marble that made ancient history feel very real. i can't believe that we are sitting on the steps that caligula may have walked on. it's amazing. she told us the water pipe by our feet was installed by caligula's successor, his uncle claudius. his name is stamped on the pipe. one of the most remarkable things about caligula is that he lived to become emperor at all. the emperor before him, his adoptive grandfather tiberius was suspected of killing caligula's father, mother, and two brothers. and when caligula turned 19 he