What are some examples of Roman or Ancient Greek architecture outside of major cities in Italy, Greece, and Croatia?

There are 100's of examples of Neo-Classical in the USA. To name just a few: The Franklin Institute has a huge dome in the entrance. This dome is almost an exact replica of the dome of the Pantheon. Image credit Bmazing on Flickr. The 3 Branches of the US government each have a building in the Greek style. They all use Greek columns, and the Supreme Court building closely resembles a temple.

I'm not exactly sure what you mean by major city so i dared include Croatia anyway...also if you want to avoid the tourists just come outside of tourist season the difference will be enormous. Here is a few examples from Pula, Croatia (population 75000) my home town. This one is called the "Dvojna Vrata" (twin gates) "Zlatna Vrata" (the golden gate) (note above: the statue in the back is Irish author James Joyce...he lived in that house) The Temple of Augustus and a Basilica The "Arena" Colloseum (second largest still standing in the world) And Split, Croatia  with the Palace of Emperor Diocletian (the palace is actually taking most of this picture...its kinda hard to see whats going on as all of these monuments are still used as residencies and businesses) There are many more examples ranging from villas to whole towns left in ruins but here are the main few notable ones from Croatia. Croatia doesn't have very many Greek structures (if any at all) since this was the place where the Illyrian tribes ruled...the Greeks never won a battle in Illyricum try as they might. Also I haven't Included any Byzantine structures in this and those are everywhere around the coast.

There are many fine Greek and Roman cities in Libya, of which Leptis (or Lectis) Magna is the most famous. Syria has some fine cities too, but Jerash, in Jordan, is perhaps the most impressive. Of the places I've been to, only Pompeii beats it. I am sure Turkey has some fantastic places too, but I have only been to Istanbul.

The Roman http://en.wikipedia.org/wiki/Aqueduct_of_Segovia (Spain): The Roman Theater at Mérida (Spain) The Roman Bridge at Cangas (Asturias, Spain) The Roman Bridge at Alcántara (Spain)