The major interior space, the Potomac rotunda, balloons under a domed ceiling with an oculus , reaching a height of 120 feet.
What could have swayed Capponi away from the plan for an oculus and toward the tall, narrow shape employed by Marcillat?
At the top of the columns a concrete-on-steel deck platform forms the oculus of the interior dome.
A round stained glass window will be installed above the oculus (opening at the top of the dome).
At the centre of the dome is an oculus , a circular hole, which is the only source of light.
The sun streams in through the open oculus , tracing a circular disk across the walls and floor, creating a walk-in solar observatory.
The oculus window will complement two large stained glass windows that have been installed in the third-floor ceiling.
The oculus windows depicted in each of their two cells illuminate the figures with an otherworldly silvery light.
Each of the upper study areas has an oculus in the floor revealing its counterpart below.
Either way, feeding a signal from a microphone placed in the oculus gives a real audio picture of the size of the space.