I'm a big fan of adventure seeds, locations, and other game components I could easily incorporate into my campaigns, so I was happy to see The Ruins from Headless Hydra Games as a completely free download.
This short pdf features an interesting location - the title ruin of a temple in an ages ago abandoned temple - including maps and encounters. The encounters in the book are using the Pathfinder system, and ranging from EL 4 to 7, so maybe an average party level of 5 or 6 would be recommended. On the other hand, I think it's not hard to "populate" the ruins with appropiate creatures, if you play another RPG.
The location
The location the characters could explore is an acient and forgotten temple of the centaurs, close to the city of Mor Aldenn, the so called City of Mages. (the setting is available here) Thankfully, it could be easily integrated into other settings, where an abandoned centaur temple makes sense. Of course, you may even change the centaurs into something entirely different...
Currently only the top three floors of the temple is aboveground, as the rest sunk into the earth during the years. It's currently populated with wandering monsters, like molds, rats and rust monsters, but it hide a big secret in one of it's long abandoned chambers.
Integration into a campaign
The best part, that the location is easy to include into a campaign. It's entirely possible that the characters are after some of the rumors regarding the area (about the ruins of giant elves...), or they may find it by coincidence. Regardless, the final secret of the temple could lead to further adventures, or to even a long-term campaign based on what the GM want.
It's also easy to expand upon the location, as you may decide that the underground parts are still reachable in some way. Maybe through the unstable floor, or maybe the characters could clear the ramp leading downwards. Also, it's quite possible that several other buildings remained relatively intact in the area, the same way as the temple.
Final words
I think it's a fine little supplement, but most of the encounters are somewhat uninteresting, so without further ado I give it 4/5 points.
Zoltán "Cain" Mészáros