One North LaSalle- Bronze Grille

This building has what may be the coolest lobby in Chicago.  Think black, gold and green. But the ornament surrounding the entrance is pretty amazing too.  The drawing to the left is a small detail taken from one of the entrance piers. I think I finished it in 2006. 

But some of the most interesting elements are the large bronze grilles  above the entrances. They're remarkably precise and seamlessly organic.  I'm still trying to figure out just how it achieves this effect.

The grid is created by starburst patterns comprised of four teardrop shapes, two large and two small opposing each other.  These create star shapes which alternate between horizontal and vertical orientation.  The points of the teardrops are connected to create either horizontally or vertically oriented diamonds.  Four of these diamonds are connected by a square rosette into a larger starburst pattern.  The triangular spaces between the large and small teardrops are filled with geometric patterns radiating inward.

 The small teardrops point towards each other creating a cross with tapering ends terminating at the square rosettes.  In the center of this shape is a large round rosette made out of petals and overlaid with  four blossoms. Fascias radiate out for this intersection, wrapped in vines, flowers and leaves.

I tried to capture a module of sufficient size to convey how the pattern would repeat itself.  Any larger and I would have gone a bit crazy.  I've also added a digital color overlay, although the original will probably get a watercolor wash at some point.

Have I mentioned that this building was designed by Vitzhum & Burns and completed in 1930?  I've got to work that in somewhere... Also, it's been a Chicago Landmark since 1996.