Perhaps the first thing that cross our minds when we see a big hole on the ground is a meteor impact. This is not an impact crater though. This is a huge round chasm, at Kamariza area, Lavrio, Greece. It was created, millions of years ago, when the roof of a big cave collapsed. The diameter of this geological formation is 120m and the depth 55m. It is also significant for paleontologists because it probably hides at the bottom fossils from trapped animals. This is a multi-shot combined in one image. The shots were taken while the Sun was low, around 8.50 local time. The camera was facing to the west. Note the elliptical shadow at the chasm's wall, similar to what we see at lunar craters near the terminator.
Canon EOS REBEL XTi, 07/09/2008, 08:48 - 08:50 (UT+3), Shutter Speed 1/160, Aperture Value 8.0, ISO 100, EF-S17-55mm f/2.8, Focal Length 17.0 mm, Combined at AutoStitch, Processed at Photoshop