Between 2008 and the end of 2010, six New York City bridges will turn 100 years old, and the newly formed New York City Bridge Centennial Commission will be making sure they're adequately feted. The six centennial spans are the Madison Avenue, Manhattan, Borden Avenue, Pelham Bay, University Heights and Queensboro bridges.

The celebrations were announced this morning by Deputy Mayor Edward Skyler and other officials at Tramway Park the base of the Queensboro Bridge. Events will include exhibitions of original designs, rare tours of the historic bridges, "bike-boat-walking tours," and other festivities for each bridge as they hit the 100 mark. We take a close look at the six birthday bridges below.