From Roy Chapman Andrews' excellent book 'Across Mongolian Plains' published in 1921.
Not far beyond the Custom House is what I believe to be one of the most horrible prisons in the world. Inside a double palisade of unpeeled timbers is a space about ten feet square upon which open the doors of small rooms, almost dark. In these dungeons are piled wooden boxes, four feet long by two and one-half feet high. These coffins are the prisoners' cells.
Some of the poor wretches have heavy chains about their necks and both hands manacled together. They can neither sit erect nor lie at full length. Their food, when the jailer remembers to give them any, is pushed through a six-inch hole in the coffin's side. Some are imprisoned here for only a few days or weeks; others for life, or for many years. Sometimes they lose the use of their limbs, which shrink and shrivel away. The agony of their cramped position is beyond the power of words to describe. Even in winter, when the temperature drops, as it sometimes does, to sixty degrees below zero, they are given only a single sheepskin for covering. How it is possible to live in indescribable filth, half-fed, well-nigh frozen in winter, and suffering the tortures of the damned, is beyond my ken – only a Mongol could live at all.
The prison is not a Mongol invention. It was built by the Manchus and is an eloquent tribute to a knowledge of the fine arts of cruelty that has never been surpassed.
I have given this description of the prison not to feed morbid curiosity, but to show that Urga, even if it has a Custom House, a Ministry of Foreign Affairs, motor cars, and telephones, is still at heart a city of the Middle Ages.