Small stones are stacked.

“The whole concatenation of wild and artificial things, the natural ecosystem as modified by people over the centuries, the build environment layered over layers, the eerie mix of sounds and smells and glimpses neither natural nor crafted- all of it is free for the taking, for the taking in. Take it, take it in, take in more every weekend, every day, and quickly it becomes the theater that intrigues, relaxes, fascinates, seduces, and above all expands any mind focused on it. Outside lies utterly ordinary space open to any casual explorer willing to find the extraordinary. Outside lies unprogrammed awareness that at times becomes directed serendipity. Outside lies magic.”
― John Stilgoe