Not the OP. I found the Palatino ruins to be extremely impressive, and the Colosseum to be a "just a bunch of rubble". It's just not a good looking building, and the areas that are open don't let you see anything that I found particularly interesting. It's big, and well built, and it's interesting how similar it is to a modern day stadium. But it's just a stadium. Vising the Forum and the temples on the other hand has fascinating, and made think about how life in antiquity would have been.