7. The Cantilevered Marble Staircase in City Hall is One of the First of Its Kind in the United States

Betts tells us that the keystone-cantilevered marble staircase is one example of how the rotunda was a feat of engineering during the time. The technique, which essentially means that the top step and the bottom step act as an arch, locks the construction into space and allows the outer edge of the staircase to be unsupported. The staircase was one of the first of its kind in the United States.

The railing is of wrought iron, a “fairly common, somewhat humble material,” says Betts, which was in line with the aim of this space to convey openness, accessibility and transparency.

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