More of a Labyrinth than a maze, since it has only a small number of very short dead-ends. The majority of the maze can be solved by simply picking a direction at at random, most paths eventually lead to the goal, just with varying lengths.
A map of the Millenium Maze: <a href="https://i.etsystatic.com/33392302/r/il/e40c9a/3604868640/il_1140xN.3604868640_gesp.jpg" rel="nofollow noreferrer">https://i.etsystatic.com/33392302/r/il/e40c9a/3604868640/il_...</a>
Not free, but not a short walk from where I live is the Hampton Court maze, which is the oldest hedge maze in Britain:<p><a href="https://en.wikipedia.org/wiki/Hampton_Court_Maze" rel="nofollow noreferrer">https://en.wikipedia.org/wiki/Hampton_Court_Maze</a>
There are loads of gaps which pretty much ruin the maze. The photos here have been very kind. It's really not worth a trip, I'm saying that as someone who lives 10 mins away and has kids. However, the tiny zoo there is a good visit.