We walked from Maeshowe, a Neolithic burial chamber, to the Stones of Stenness. Overcast and cloudy. Maeshowe is aligned to the Winter Solstice when a shaft of sunlight beams into the chamber through the long low entrance tunnel. This was the signal for the beginning of a winter festival to celebrate the turn of the year. All the sites around, including the Stones of Stenness and the Ring of Brodgar, are aligned to the Solstice.
See http://www.maeshowe.co.uk/maeshoweabout.html for info and pictures of the interior.