Arkham Mansion--Part 1

Locate a Route into the Arkham Mansion

Before you go running around, you should know that the enemy has begun to deploy snipers to take you down. The first two of which are holed up in each of the nearby guard towers, so at least you know where to find them. As such, your primary objective should be to target them first, which you can easily do by grappling to each tower and sneaking up behind them for a Silent Takedown. Oh, and make sure to grab the Interview Tape from the table within the closest tower. You can also find a Secrets Map inside left security building (near the entrance to the Intensive Treatment center)--get inside by grappling to the roof and detonating the weak section.

Once you've cleaned out the area, head through the door leading to Arkham East (found, fittingly enough, on the eastern side of the area). Inside you'll have to take on a small gang of enemies before exiting out the other side into Arkham East proper. Be careful, as Arkham Mansion is guarded by four snipers: two in the nearby towers, and two more just above the entrance. Like before, grapple up to the guard towers (head for the one on the left first) and use the Silent Takedown on both snipers. Also, be sure to check inside the second tower for an Interview Tape. Now you still have the two above the entrance to deal with. We suggest crossing the northern end of the field to evade their sight, then hug the mansion's wall to pass underneath them. Now grapple to the high-ledge, just right of their location, then glide-kick the nearest one in the face. While he's stunned, focus on taking down the other sniper, before returning your attention to the one already on the ground.

With the snipers dealt with, you now just after the small task of finding a way into the mansion (the main entrance is blocked by an electrified gate inside). To get around this, grapple to the ledge just above the main entrance to find a ventilation grate in the wall; pull it off with the Batclaw then grapple inside and go through the door.