Wonders of the World - Segovia

This truly is a wonder of engineering, considering that it's been working for nearly 1800 years.  It has had some renovations in the intervening years but basically it is the same as when the Romans built it.  It's the aquaduct in Segovia, Spain and it was built to carry water to the town.  There is no concrete in it, only the weight of the huge granite blocks keeps it upright.  Considering that for the last 100 years or so, it has had modern traffic rumbling through it's great arches, it stands firm and remains one of the great wonders of the world in my book.  You can read more about it at http://en.wikipedia.org/wiki/Aqueduct_of_Segovia