A big hunk of glass

From Digital Photography Review:

The world's largest optical lens has been delivered for a $168M, 3.2-gigapixel telescope camera
The SLAC National Accelerator Laboratory in California, the lab overseeing the design and fabrication of a 3.2-gigapixel digital camera for the Large Synoptic Survey Telescope (LSST), has successfully received the shipment of what may be the world's largest high-performance optical lens. The announcement was made earlier this month by the Lawrence Livermore National Laboratory (LLNL), where researchers designed the optical assemblies for the LSST.

Here is a two minute fly-through of the scope (no audio - just video):

Impressive - heading up to Chile's Atacama Desert. Would not mind going there for a visit, looks austere and gorgeous.