Grass areas are seldom level enough to set a gazebo without any preparation. The gazebo may be set on a concrete pad, patio, deck, or bed of crushed stone. A good way to prepare a foundation is to cut out 4″ to 6″ of sod and fill it with ¾” crushed stones. You will likely want to frame the pad with timbers if the ground is not level since you will then need to dig deeper at some places and may need to hold the stone in place on one of the sides. The foundation needs to be level for your gazebo to be level. To help prepare your site you may want to check with Eli Stoltzfus at Bedrock Foundations (484-712-8828), Gid Stoltzfus at Better Built Pads (717-629-0968), Jake Lantz at Firm Foundations (717-629-0689), or for the Lansdale area only Larry Bergey (484-336-9481).