OLD COPPER CULTURE II, MN
MONKS MOUND, CAHOKIA, ILLINOIS
HOUGHTON’S PETROGLYPH
ITA LETRA, PARAGUAY
MYSTERY MOUNTAIN (I), WV
STONEHENGE: DISCOVERY OF AMERICA
SENTINEL ROCK, VERMONT
METAL TRADE IN THE BRONZE AGE
CIRCLE CROSS CARVING, MI
MYSTERY MOUNTAIN (II), WV
SWAN STONE, ILLINOIS