The Leaning Tower of Pisa
The Leaning Tower of Pisa is the world's most famous
construction mistake.  The architect, Bonanno Pisano,
found his bell tower starting to lean almost immediately  
after he began to build it.  And the lean kept increasing
through the centuries, a tourist bonanza for Pisa, that
would end if the tower leaned too far and fell.
This picture was taken in 1994, prior to a major
engineering effort to stabilize the tower and reduce the
lean by 10%.  The tower was also closed to visitors.  I
had climbed it back in 1986, great fun, but disorienting.   
Returning to Pisa in 2001, I wanted to help the tower by any
means necessary; lending a hand, or at least a few fingers.  
The lean does appear less than in the picture above taken
seven years earlier.
The lean remains apparent from the tower's base.  In 2001,
there were counterweights and cables to the left of the base
trying to assert some control.  The project was declared a
success, and the Leaning Tower opened to visitors again.
The Duomo (cathedral) on the left does not lean and sets the
standard for vertical in Pisa.  It's bell tower provides a stark
contrast in this 1994 picture.    
Still leaning after all these years.
Italy
If you have a high speed internet connection, watch the Intrepid
Berkeley Explorer's free video that is 100% Italy,  by clicking
on  
Gondola With the Wind 2  ; also see Rome, Florence, Pisa,
and Venice by clicking on the earlier
Gondola With the Wind