In May/June 200, when I was in Rome with my young son, we tried to find the Domus Aurea: there were no signs, nothing. I think we were walking on top of it all the time.
I am fascinated by the architecture of it: the eight-sided room of which three sides opened to the gardens (some of which, yes, were overbuilt by the Colosseum). 
Reconstructed images are even more beautiful. I have some at school but not at home.