Michelangelo’s David has weak ankles.  They are full of micro-fissures.

David (1504)  5.17 meters (17 feet) ; in the Galleria dell’Accademia, Florence  (photo by Rico Heil, licensed under Creative Commons Attribution-Share Alike 3.0 Unported)

And now if they build a high-speed train nearby, he  might come crashing down like Goliath.  See this article just published in the Daily Telegraph.

The following is  a post on those weak ankles published here on August 187, 2007.

A figure with its legs apart may not seem too daring or revolutionary. But IN STONE it isn’t wise. How are those skinny legs going to support all the weight of the rock (torso and head) above them? In fact, there is too much weight on David’s ankles, in spite of the two tree trunks there to shore them up. There are cracks, especially in the right one.

See article

A block of stone isn’t a man, even if the great Michelangelo can make it look like one. Living things have learned to defy gravity with muscles (how do the plants grow UP?) but a stone just sits and obeys the law. Usually a figure like the David would have been conceived for bronze, which is stronger and can handle, i.e. give support to, representations of almost all human postures and pirouettes.

Here are some figures unsuitable for stone sculpture:

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