An early copy of Wren's lost original drawing shows how the auditorium would have been roofed. Little is known about the details or even the size of the vestibule, but from the criticisms of another architect, Sir Roger Pratt, in 1673 and a brief description by Wren's son we know that it was large, had three porticoes, and a tall dome without windows above a circular drum with windows between columns.
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