The first is a ruin generator. Basically, you roll an exploding d4s to see how many buildings are left relatively intact, then roll that many d20s on the table below. From there, it's up the DM to decide on a theme, usually Roman, Greek, Egyptian, Babylonian, or whatever else you're familiar with an start bull shitting (later tables will help with that).
1. Tower –Sprawling from the ground or connected to a wall, previously inhabited by soldiers or magic-users.
2. Citadel – Ruined by siege of decay, but many still house historical artifacts and vaults filled with priceless treasure.
3. Bathhouse – Complete with running water and aqueduct for Roman-esque ruins, otherwise built around a hotspring.
4. Temple – Build in honor of some Greco-Roman, Babylonian, or Egyptian deity or hero.
5. Theater – Don’t forget the primitive steam powered turbines to open and close the curtain before the back wall.
6. Coliseum – Remember, Roman coliseums could be flooded for naval events and had underground areas for gladiators to train and rest.
7. Market – Outdoor market semi-percent market stalls or a vault and barrel enclosed area.
8. Wall – A big thick, stone or palisade with one or more gated or open entrance.
9. Triumph or Commemoration – Usually in the form of an arch or statue.
10. Manner – Big house of a big personality. Should be unique in some way.
11. Earthen Ramp – sometimes equipped with a trench of more.
12. Houses – A few, a bunch, typically one or two room stone, brick, or wooden hut.
13. Brothel – Many ancient brothels had pictures of the woman’s specialties depicted in mosaic tiles above her downway.
14. Stone Road – Typically leading out of the city to some other point of interest
15. Underground Sewer – Not strictly historical, but can lead to some fun dungeon-esque adventures.
16. Stables – The don’t just have to be for horses, either.
17. Farms – Overgrown farms and ruined farmhouses dot the landscape. 50% chance of permanent inhabitants.
18. Dungeon Entrance – Roll again to find out where.
19. Incomplete Construction – Half finished when abandoned.
20. Still In Use – Roll again to see what sort of building is still functions amidst the ruined site.