Final Fantasy VII/Temple of the Ancients
It's time to head out of the park and to the Temple of the Ancients. Your team consists now of Cloud, Aeris, and one more lucky winner. Along with the recommended level, you should seriously consider getting the Big Guard Enemy Skill if you don't have it yet.
A good spot to train at this moment would be the island with the Temple of the Ancients itself. You can't miss it, once you get going with Tiny Bronco; go southeast of Gold Saucer and follow the island chains, at the end there's a big island with a forest and a pyramid in the middle. Of course, the pyramid is the Temple of the Ancients. The only annoying thing is that the island is inhabited by Slaps, who are mosquitos. They cause the party to get poisoned, saddened, and berserkified, and cause just about as much damage as normal mosquitos in general.
Stock up on Tents, Elixirs, and anything else you'll need. There's no need for Tents inside the temple, but they're very useful if you're training up beforehand.
 The Temple
Aeris will have a prostration fit once you reach the temple, because her ancestors are around. A black-caped guy comes out and collapses. Sephiroth is somewhere in the Temple, and at the entrance you find out he has stabbed Tseng with his sword. Tseng gives the Keystone to his (as you learn) old friend Aeris. With the help of the Keystone, you get into the Temple.
The courtyard will look complicated, but it's really not. There's one correct path to follow, and the temple guardian - an old man in a blue robe - will show you the way. Basically, use stairs and the vines and doorways and such. You can pick up Trident (Cid's weapon), Rocket Punch (Barret's weapon), Lucky Plus materia, Mind Source, Turbo Ether, and Silver Rifle (Vincent's weapon). There's one chest you can't get to right now, and one doorway you can't access.
At the end, you reach a door that leads to a single corridor with big stone wheels rolling through it. The wheels have a gap in them; the idea is obviously to run to the center of the corridor right where the gap happens to be, then run to the next wheel's gap, and so on. You'll get flattened if you fail, but you can just try again.
At the end of the corridor, the stones somehow disappear, and Aeris and the Ancients will lead you to the pool and show you a vision about what happened a bit earlier. Grab the Morph materia from the ground - it's highly useful. Continue along the corridor, and the guardian waits there, giving you the option to restore HP and MP for free, or save the game.
 Time Guardian
Press on and you find yourself in the Time Guardian's room, with a clock face puzzle. You must use the clock hands to cross. The instructions on controlling the time are shown, they should be simple enough. If you get knocked down from the hands, you end up in a small room where small dragons attack you. In that room there's a chest with the Nail Bat (Cloud's weapon). The door leads back out.
Here's what happens in the various rooms.
|I||A chest containing a random encounter.|
|III||A chest containing a random encounter.|
|IIII||A chest containing Princess Guard, Aeris' ultimate weapon.|
|V||Leads to the inaccessible roof in the courtyard, with a chest containing Ribbon. This is a very rare item, be sure to grab it!|
|VI||Toward the hall with the murals. This is where you should head once you're done. Check the other rooms first!|
|VII||A chest containing Trumpet Shell, a weapon for Cait Sith.|
|VIII||A chest containing a Megalixir.|
|X||Where you came from - back to the corridor with the pool.|
|XII||The back door of the temple. You'll get here later.|
 Mural hall
Once you head through the six o'clock door, you find yourself in a room with a lot of caves and locked double door. The idea is to catch the temple guardian. You need to memorize where each passage seems to lead, and try to get yourself into the same corridor with the temple guardian. Or, you can cheat and just go in the same corridor each time - you're bound to collide sooner or later. The guardian, once again, gives you the option to heal up or save. Open the chest on the lower level to receive a Work Glove for Tifa.
Once you head through the double doors, you find yourself in the mural hall. Sephiroth shows up, talks about his true plans, and makes Cloud seriously freak out too, before disappearing. After the cutscene, it's time to fight a big creature.
You get a Dragon Armlet, a really nice armor, and after the fight, you see Bahamut materia floating right in front of you. A big summon materia. Now, go back to the end of the mural hall. There's a model floating about. Shake it. This destroys the Temple, but Cait Sith calls you and offers to grab it while you run outside.
 Losing Aeris
Head out, and the guardian is still here. Heal up and save. This would also be a good time to make sure Aeris doesn't have any unique armor equipped on her. Feel free to give her tons of good materia and an accessory, though. That is obviously needed here. Now the Time Guardian room is locked so that the only way out is through the 12 o'clock door, which leads out of the place.
Next comes a long cutscene where you first see Cait Sith get flattened, you get a hard-earned Black Materia, and then Cloud gives it to Sephiroth. Cloud freaks out, and Cait Sith no. 2 shows up to replace his predecessor. Cloud faints, Aeris shows up in his dream, and as Cloud wakes from the nightmare, you find that Aeris has gone to the Forgotten Capital.