Stone structures built by the Maya.
  The Pyramids of Mexico.  Additional photos of Mayan structures.
  Inca Ruins.  Note the degree to which the large stones bear on and against one another.  Also look for the simple stone header above the doorway.
  Egyptian temples including some that were carved into the mountain.  Look for the photo taken within the museum.  Can you see the lintel stone above the doorway?
  Use the interactive materials lab at the Building Big website to see if stone (or concrete) can resist tension.
  A little farther back in time to the Minoan civilization.  Look for the arch in the photo at lower right.
  A quick look back at the history timeline will let you see that the Romans did not invent the arch.
  As you can see from the linked examples, stone structures tend to look like the drawing at left - thick walls and deep stone lintels.  We are free from the drawbacks of wood, but there is a problem: stone is weak in tension.   

  The long span shown at right highlights the problem.  If the stone beam bends, tension stresses will initiate a crack near the point of maximum stress....and the beam will fail.  This fact was known by ancient builders and this limitation expresses itself in the historic architecture of many cultures.