Building treehouses and forts is a treasured childhood pastime. If you’re planning on renovating, but have a sentimental attachment to your old windows and doors, a treehouse or backyard fort is an excellent way of putting them to good use. We’ve gathered some of our favorite treehouses off of Pinterest that feature old looking or repurposed windows and doors. Ready for a trip down memory lane? 1.  The windows on this ‘bridged beauty’ feature worn wooden frames and traditional crisscross grilles, for a sense of style and adventure. 2. Was there ever a more ideal place to swing? We love the white shutters and classic-style windows on this cliff-facing clubhouse. 3.  What an excellent use for a rustic door and a traditional swinging-style window. This rugged, patio tree house could be mom and dad’s hideout. 4. The swinging, shutter-style windows on this backyard tree house would make an excellent compliment to any garden.…