You'll find yourself on the playground. Barret will be pretty broken up that Sector 7 was destroyed, but he'll be a bit hopeful when he learns that Marlene might be safe. He and Tifa will join Cloud after a brief psychotic break. You can run back up and to the right and grab the yellow Sense materia now or on your way back through to Wall Market. Head toward Aeris' house. To get there, go down through the ruined streets, then to the right and up. Run in to the glowing yellow area to the right of the run-down camper. Back at Aeris' house, you find out about the Ancients and Aeris' mother. Barret will meet up with Marlene.
Back to Wall Market
Barret will suggest that Wall Market might have something that might help you get to the Shin-Ra headquarters, so head there. Don't forget to pick up the Sense materia in the playground if you haven't yet. It's a good chance to stock up with all sorts of stuff. The people will discuss about how the neighboring sector was crushed, the porridge is all ruined, and how all sorts of stuff rained down - and that the weapon shop man grabbed it all. The weapon store man - the one who's constantly fixing up the tank, not the clerk - tells you that you need batteries to get up to the plate. They're only 100 gil, so go ahead and buy them.
Extra: If you enter Don Corneo's mansion again, you can pick up the Phoenix Down in the lackey's room if you were chosen by Don previously and Hyper if you missed it in Don's bedroom, and in the basement area you will find a man chained to the top of a coffin, he will explain that Don Corneo went somewhere with Shinra and then run away.
Stock up on Lightning materia, have at least 3, one for each party member at time. You are heading to a highly technical place next, full of mechanical enemies who are weak against lightning.
The long climb
As you pass Don Corneo's mansion, a bunch of kids will tell you about the cable that just happens to hang down all the way from the World Above and lets you climb the sector wall. After you get up, the place is again fairly straightforward: The yellow sockets need batteries inserted in them, and these let you advance. The batteries can be found at the weapon shop, you need to talk to the old guy in the back he sells them for 100 gil.
There is a frustrating section involving leaping from one side of a gap to the other side by using a swinging bar. Timing is really important. The best way to proceed is to pick some static spot of the background, and hit the button as the bar is at that point, and if you don't make it adjust the spot. The right moment is when the bar is swinging towards Cloud, right before it hits the second prong and pretty close to him, but not quite there.
Extra: If you wish to keep a battery for a complete inventory at the end of the game, you can do so, by not using the final Battery, you do not really need to use it because it will only give you an Ether, and will not affect game progression.
Entering Shin-Ra HQ
You can save at the front entrance of the Shin-Ra building. Tifa begs you to sneak in. To sneak in, head left and use the side entrance door. You need to climb all the way up to the 59th floor. The only spoils on the long climb are a lone Elixir, and the conversations between Tifa and Barret. You can also do what Barrett suggested and just walk through the front door to the Shin-Ra headquarters. As soon as you head in, you will get attacked. When the battle is over, you can chase the group of people around the lobby, or you can just jump on the elevator at the back of the lobby. However, security alarms start going off, and you'll have to fight random battles on the elevator until you get to the 59th floor. If you get lucky, you'll run into some Shin-Ra employees and they'll just leave you alone.
The Shin-Ra building is where you finally get to take someone to task for crushing Sector 7. You'll also pick up a new party member and after escaping, find your way out of Midgar to the overworld map where the rest of the game takes place.
59th floor
There isn't much to see here. Beat up the guards before they make much of a ruckus and grab their Level 60 Keycard. The robot guards are very susceptible to Lightning, but Ice works pretty well too. Give each party member Lightning materia, hammer away with it, and you can kill each of the guards in one turn. If you don't have enough Lightning materia, at least equip one person with a Lightning+All combination so that you get a good spread on your first hit, then just Lightning/Ice/Assault Gun and you can still normally take the guards out in one turn.
60th floor
Time to sneak past guards. Head to the room on the left, open the door and head to the statue when the guards aren't looking (you can move to the first statue no matter what the guards are doing). When the guards aren't looking, scoot across the gap between the pillars, one at a time, until you reach the middle and Cloud leaves your control. At this point, you use 
to let Barret and then Tifa know when it's safe to cross a gap. Remember, any time the guards aren't standing still they aren't looking! Then, do the same process for the right side of the room, note that the distances are shorter and the guards run now, so be careful.
If you get caught, the guards will attack from both sides. In that case, use Bolts or Bolt/Ice/Gun again. Luckily, if you absolutely don't manage to get through with five tries or so, the torrent of guards will eventually end. The team isn't very happy about this, but at least you tried!
61st floor
This is the employee lounge or general area. Luckily, the door is busted so you won't need a keycard to get to this floor. Once inside, talk to every person in the room. When asked about Aeris reply with: "...", you get a the Level 62 Keycard for your trouble.
62nd floor
Speak to the guard in the hallway then enter the room. The Mayor will help you if you manage to solve his riddle. Speak to the guard once again for help to the riddle. Look at each library room's sign beside the door. Each room contains books on certain topics corresponding to the door sign. Each room has three shelves. Each shelf has two books, stored on either ends of the shelf. Your task is to find the book that doesn't belong in the library room in question. For example, "16 Modern history of Midgar space program vol. 1" that has somehow been filed in the Urban Planning library. When you find the out of place book, count to the indicated letter, ignoring spaces and punctuation, from the beginning. In the example, the sixteenth letter is "M." Each of the four library rooms has one misplaced book. Arrange all four letters to form a word that corresponds to the password list presented by the mayor. Be noted, the password resets every time.
The Mayor will give you the Level 65 Keycard for guessing right eventually, and an Elemental materia if you guess right on the first try. You should equip Elemental+Lightning (in a weapon with linked slots) combination as it will make the character's weapon lightning-based. This gives you an attack bonus for mechanical creatures in the HQ
63rd floor
Once you reach this floor, go to the door access computer below where you come in. It will give you the ability to open three doors on this floor.
Go right, then all the way up, then left until you hit a door. Open it. Go left until you hit a second door. Open the door south of this one. Get the item coupon in the room west of the door you just opened. From there, click to jump into the air ducts. Once inside, go up the central duct to another room containing a coupon. Exit this room, and open the door to the west to get to the last item coupon. Afterward, jump into the air ducts again and go back to the first room again. Tell the computer you want to trade in your coupons, and you will be rewarded with a Star Pendant accessory that protects against Poison, a Four Slots armor that holds four individual materia, and an All materia, which should be equipped with Restore.
If you make a mistake and open up the wrong doors, go back to the door access machine to reset the doors. Remember, once you turn in your coupons, the doors won't reset anymore!
64th floor
Floor 64 is the gym. There are only a couple things here:
- The room on the far left contains a save point. It will also ask if you want to rest upon entering.
- In the top left corner of the exercise room, there is a vending machine. It costs 250 gil and whatever should come out, doesn't. If you examine it again, you have the option to bang on it, do it. You will be rewarded when you return on Disc 2.
- The locker room has a few items in it. To get them, just walk up to the following lockers and press [confirm].
- First row, third locker from the right: Phoenix Down.
- Second row, second locker from the right: Ether.
- Third row, third locker from the left: there is a megaphone that you can't collect yet. This is Cait Sith's Ultimate Weapon, so be sure to get it when you return to Midgar on Disc 2.
65th floor
There's a big Midgar model in the middle, with chests scattered around the level containing the missing "Midgar parts." Only one chest opens at a time. You must examine all missing pieces of the Midgar model and then seek that chest and return. Insert the piece to the model in its appropriate place, and another chest will open. Repeat this until the last chest unlocks. It contains Keycard 66.
66th floor
As you get in, you note that the President, Heidegger, Scarlet, and other people are gathering in the big meeting room. Obviously, it's not really wise to barge in so, head to the bathroom. Use the ceiling grate to get to the ventilation shaft, which just happens to be above the meeting room. Cutscene ensues. Listen patiently. As the meeting ends and you crawl back, you see Hojo leaving and going to the floor above.
67th floor
Here, you see Hojo adoring his new specimen, and he goes to the floor above using the elevator. Head north, save if you want, collect the Poison Materia from the chest near the door, then go up.
A brief cutscene ensues, after which you must select who will take care of Aeris. The specimen, Red XIII, is added to your party and comes armed with some free Materia. Another specimen shows up, and you need to fight it. For this fight, your party has Cloud, whoever you didn't send away with Aeris, and Red XIII.
Don't pay attention to the HO512-opt flunkies on the front: the boss will just revive them. Besides, they won't be able to hurt you too badly. HO512 will poison your party, so equip someone with the Star Pendant you found earlier. Cast fire or ice to make quick work of this boss.
Item(s) received: Talisman (accessory)
| Level | Hit Points | Magic | Weak against | Strong against | Absorbs |
|---|---|---|---|---|---|
| 19 | 1000 | 120 | - | Bolt, Gravity | Poison |
After beating HO512, grab the Enemy Skill Materia (it's where Aeris was being held), and talk to the technician standing on the catwalk for keycard 68. Run around this floor and steal enough Carbon Bangles from Moth Slashers (blue chain saw looking robots) for your team, preferably 5, as well as a Hardedge for Cloud from Solider: 3rd (the blue soldiers). These soldiers can give you a serious beating, but the Hardedge is worth it at this point in the game. Pick up the 2 potions south of the guy with the keycard, as well as from the south hallway. You can take the stairs back to the rest area on the 64th floor to heal and save at any time. Now, it's time to escape.