Star gate effect! This 3 hour and 14 minutes star trail it is my longest so far. The construction is the side view of Thoriko ancient theatre near Lavrio. It is the oldest in Greece dating to the late 6th century. A higher resolution photo is available here.
Canon EOS DIGITAL REBEL XTi, 13/6/2009 00:50 - 04:08, Shutter Speed 40 sec x 291, Aperture Value 4.0, ISO 400, Lens EF-S17-55mm f/2.8 IS USM, Focal Length 17.0 mm