It may seem like the same Swampscott skyline as one enters the town on Lynn Shore Drive, but look closer. What is it? Wow! Looming over beachfront homes like a giant butterfly, there it is. What is it? This is the giant indoor filming facility where Adam Sandler’s Grown Ups 2 will be shooting their pool scenes. That’s right, an in ground pool has been planted inside the structure, which sits just off the Swampscott football field at Blocksidge Field.