An Entire City
Ephesus is, without a doubt, the best preserved and most expansive ruined city I've ever seen. It's divided into two parts, a new city and old city as I understood it, that are connected by an amaizingly engraved marble road lined with statues and monuments. The ruins, as I mentioned, are enormous. It'll take you about 2 full hours to see just the most notable things, and maybe another 2 to explore all the nooks an crannies. This is another thing to mention: if you get a tour guide, it has its ups and downs. On one hand, they get you past the lines and give you some interesting, but not absolutely vital, information but they also tend you rush you from monument to monument.