Why does the leaning Tower of Pisa lean?

The tower leans because it is slowly sinking in the soft ground.  The Leaning Tower of Pisa is a famous bell tower at Pisa, Italy.  The tower tips so far to one side that it looks as though it would fall over.  But it has been leaning for over 600 years!

Tower of Pisa

Why does it lean?  Of course, it wasn’t supposed to lean when it was built.  Yet it began to lean long before it was finished.

Builders began to work on the tower in 1174.  The stone foundation was not built on time enough ground to support the heavy marble tower and it began to sink unevenly into the soft soil.

But the builders went on adding story after story until the tower was 180 feet tall.  Since it was finished it has leaned a little more as the years went by.

Even today little by little the tower continues to tilt more each year.  It is now leans over 17 feet to one side.  Some people estimated that the tower will topple over within the next 100 years. – Dick Rogers