Message posted by Mark on June 29, 2014 at 18:59:42 PST:
They had to look like they might be the top of ventilation shafts. They normally rise above ground so they don't pick up ground debris and are relatively small.
In Reply to: OT: all along the watchtower. posted by wheresjanet on June 29, 2014 at 15:05:12 PST: