That depends certainly on what you would accept as "mostly intact". I don't have any numbers ready, just a coarse guess. The Concordia temple in Agrigento, Sicily, http://www.mlahanas.de/Greeks/Cities/AgrigentoTempleOfConcordia.html and the Hera Temple in Paestum are among the best preserved temples from classical Greece. Intact Roman buildings in Italy, there may be more (Forum Romanum, Rome). Many bridges, since those were used and maintained. All in all it may be less than hundred that would be as well preserved as the Concordia temple. You may browse here: http://www.antikefan.de/index.php site is in German, but it's mostly pictures.

the colossuem and the Parthenon come to mind

I am sure there are many even the Roman baths in Bath England are still intact. many Greek Temples and Roman ones around the world http://en.wikipedia.org/wiki/Temple Some temples and ancient buildings, hope the link works I am not very good at them It would be impossible to put a figure on the exact amount EDITED

The answer to this depends on two things, actually: what is a "building," and what is "mostly intact." If we exclude bridges, aqueducts and walls as not being buildings (in the sense that you cannot walk around inside them), the answer is: precious few. Among civic buildings, virtually every one is a ruin except those which were converted into churches (a few temples and basilicas) or those which by design could not as easily collapse (theaters and ampitheaters). I am aware of one Greek temple that still has a roof (the Temple of Hephaestus, in Athens, better preserved even than the ones mentioned in Agrigento and Paestum) and at least a handful of Roman ones that do (Maison Carree, Pantheon, Fortuna Virilis). As for private buildings, I am not aware of a single ancient Greek or Roman house or apartment building which has survived in functional condition (places like Pompeii, Herculaneum and Ostia have impressive ruins, though, some in pretty good shape). I suspect if you wandered around the hill towns of Tuscany you might find some Roman foundations supporting buildings still in use, but as far as I know you won't find any of the Roman houses themselves - they're all long gone. So what's the tally? If by "mostly intact" what is meant is a building which is visibly more than a ruin - e.g., has a roof, or could still be used in some form (theaters and ampitheathers), I'd guess about 20 or so. Adding in "partially intact" places like the Parthenon and Paestum could triple that. Bridges and aqueducts would add considerably more. Anyways, here are some pictures of the best ones: Maison Carree (IMO the best preserved classical building in the world): http://www.tourdelamusette.com/img/NimesMaisonCarree.jpg Ampitheater (also at Nimes): http://www.livius.org/a/france/nimes/nimes_amphitheater1.JPG Temple of Hephaestus: http://granite.sru.edu/~lmiller/greece/hephaesteon.jpg Street scenes from Herculaneum and Ostia: http://wings.buffalo.edu/AandL/Maecenas/italy_except_rome_and_sicily/herculaneum/ac881914.html http://www.italianvisits.com/images/lroma-im/ostia-im/ostia-street.jpg