In Ancient Rome where did the soldiers sleep?

The rich slept in detached houses with an inner garden called domus.

Most Romans lived in apartment blocks called insulae (singular, insula, island). The poor lived on the upper floors which were the least desirable because of the extra stairs and they were less safe in case of fire and, therefore, were cheaper to rent. The apartments on these floors were small and only had small rooms for sleeping. There was no running water, heating, cooking facilities or toilets. The poor went there only to sleep. During the day they and lived outdoors. They ate outdoors, went to outdoors public toilets, and went to the public baths. The insulae were up to six or seven floors. Despite height restrictions, some reached eight or nine floors. Originally they were built in timber and mud brick, later chap concrete was used. Fires and collapses were a common problem, made worse by the fact that they were often built cheaply by speculators. Fires could spread quickly because the insulae were densely packed, often separated only by alleys. After the Great Fire of Rome (64 AD) Nero ordered that the insulae were to be spaced out, built in brick, and faced by porticos on wide roads. Even so, they remained prone fires and collapses because of poor building quality.

The middle class lived on the lower floors of the insulae which were larger and more expensive and had running water. On the ground floor there were shops and workshops.