I reached the center of Rome around Roma Termini and the first impression, after a time spent in nature and in the picturesque medieval towns, was quite terrible: floods of litter, garbage and dirt of all kinds, noise, soldiers in armored vehicles with machine guns, suspicious idividuals of all nationalities, incl. e.g. one older lady just hand-measuring her black favourite as he counted the money, with other guy preparing his shot nearby…
But it was enough to walk the marble pavements towards the historical centre, and the Eternal City has much more to offer. Actually, wherever you look your view is blocked by a world-famous monument if not thousand year old, then at least centuries old. Because I wanted to stay in Rome for just two nights, I just joined the stream of tourists, randomly walked through the most famous places in the center and looked and looked.
Comparing to Venice, the number of tourists per square meter was quite tolerable, except for isolated spots like the Trevi Fountain. One place completely free of (non-Italian) tourists that I can recommend is the Monte Mario hill, where I had a lunch with a unique (in otherwise relatively flat Rome) view of the whole city.