Sundial of the month May

Summer and winter solstice

Not a sundial like the ones usually shown here, but a solstice monument.

On a vast plain, four large tubes are aligned with sunrise and sunset on the solstices.
The snow in the photograph is a clue that it was taken on or around a winter solstice.

During daytime, holes drilled in the sides of the pipes project maps of constellations on the interior.

Satellite foto