Featured Puzzle: Plan for Trick-or-Treating

One eager ghost is really looking forward to trick-or-treating, and is already planning a route through the neighborhood. Can you find a route that circles the entire neighborhood, visiting every house one time?

Draw a single loop which passes through every cell of the grid. Naturally, you have a few restrictions:

• You must make a 90-degree turn when passing through a house. The loop never exits the opposite side of a house it enters.
• While traveling between houses, you must make exactly one 90-degree turn.
• All lines must be placed in orthogonal directions, connecting the centers of adjacent cells.
• The solution has only one loop which may not cross itself.