Ascent
Start climbing the stairs and eventually you'll get to the top. Bust through the door and you'll be surprised by a stranded. After a moment, he'll get splattered so keep your head down. Check the nearby bathroom for a Longshot to help you with the One-Shots the grubs are using. Kill the snipers and the next building and then travel to the end of the hall. Enter the next room on your right and you'll be attacked by a few Boomers. Kill them and the next room should have Grubs and a hole leading down to the lower floor.
Deal with the grubs and drop through the hole in the floor. You'll be attacked by Wretches as your make your way forward. You'll see a dead Grub body on the ground with a bucket over his head and a smiley face painted on. Go towards that and turn left into the office. Behind the desk, activate the lion's crest just left of the bookshelf. Behind this bookshelf should be a whole stash of ammo and weapons. Stock up and then climb out the window of the office. Halfway between the window and the Crimson Omen to the left will be your [COG Tag].
Head back the way you came and instead go the other way. You'll stumble across a few Grubs before entering a room with a TV. To the right of the TV will be a bunk bed with Frag Grenades in front. Grab the grenades and then head for the nearby stairs. Climb to the top and go through the doors onto the roof.
On the Roof
You'll almost immediately get attacked by Grubs. There are a few on this lower level but be careful as you climb to the top level. Up on the top level, you'll find far more Grubs and Diggers. You can use the pipes to get around while staying in cover but once you've finished these enemies, a Reaver will land on the roof and attack. You'll need to get moving and vault over the pipes to escape from the Reaver's attacks. If you don't have a Boomshot, grab a Digger Launcher and use grenades instead.
Head over to the tower and shoot the cables holding it on to knock it over. Cross to the next building and you'll find Drones, Theron, and Snipers on the roof. Similar to last time, there are plenty of pipes to give you cover and allow you to move around. Some of the Theron should be carrying Torque Bows and if you're low on explosive ammo then this is a good alternative. When the Grubs are gone, another Reaver will land on the roof and using the Torque Bows can really help you out.
With the Reaver done, you can now enter the restaurant.
