Seattle, WA

On Mt. Baker ridge, above the I-90 tunnel, a line of 12 basalt stones stand, each with a perfect vertical line cut down their centers.

On the summer solstice—the longest day of the year—the stone at one end will perfectly align with the sunset, which will set 36 degrees north of due west. On a certain day of each passing month, the next stone in the line will frame the sunset. The last rock marks the winter solstice, the shortest day of the year, when the sun sets 36 degrees south of due west. The middle stone represents the equinoxes, when day and night are roughly equal in length.

University of Washington astronomer professor Woody Sullivan measured the angles necessary for the construction. The small park was opened on the 2009 spring equinox on March 20.