Quotation from: The Gods of Mars

Written by: Edgar Rice Burroughs

Through a massive arched gateway the blacks poured in to take their
seats, while our guards led us to a smaller entrance near one end
of the structure.

Through this we passed into an enclosure beneath the seats, where
we found a number of other prisoners herded together under guard.
Some of them were in irons, but for the most part they seemed
sufficiently awed by the presence of their guards to preclude any
possibility of attempted escape.