I'm going to give it a try, but I'm still unsure if this is what you are asking.
In your example sentence
Vado a Roma in estate e mi piacerebbe davvero vedere il Colosseo la mattina presto, prima che le folle arrivino.
There are 3 points that one could be able to stress / put emphasis on according to what he wants to emphasize (any single or combination of them):
Vado a Roma in estate e mi piacerebbe davvero vedere il Colosseo la mattina presto, prima che le folle arrivino.
In estate: You want to stress that you are not going "soon", but in summer time. Maybe used for example because you want to stress that you are not conflicting with work (summer is usually a more relazed period for most professions), or because it's warmer, or whatever.
davvero: You don't want to just visit the Colosseo, you crave it, you really can't wait to see it.
la mattina presto (or just presto): you stress that timing is crucial, subsequently explaining in the subordinate sentence why that's the case.
I don't think one could stress any other part of your example sentence, lest sounding a bit unnatural.