City 18 is one of the poorest Universal Union-controlled Cities because of its small size, yet it has been confirmed that it houses one of the best Civil Protection forces than almost any other City. Citizens rarely violate any of the Universal Union rules, yet most of the violations get performed as of the highly restricted and dangerous District 6. Unlike District 1 and 2 (Public Areas), District 6 has been restricted completely since Resistance activity has been recorded to be very high inside. Like many other cities, City 18 has a large industrial slums area known as district 6, an area that is blocked off from most ends, but, with a well-developed plan, can be breached. The slums are made up of alleyways, catwalks, and small buildings such as restaurants and shops. The slums provide shelter for refugees and absconders, but the slums are also littered with mines, victim to periodic searches by Combine forces, and are home to groups of thugs and anarchist unions of fugitives who seek nothing more than to create chaos both inside and outside of the Universal Union's reach. The only ways to access the slums are to go through Checkpoint 1 (usually, on the majority of servers, built near the ration distribution terminal, or the old theater), its neighboring subway tunnel, or the 45 Apartments catwalk, however all ways require both skill and luck when being used.
Unlike City 08 or 17, City 18 does not have as much Civil Worker's Union support. It only has a few cafes and a clinic. Though, nobody notices the dull, gray and boring atmosphere of City 18 because of its high level of Breen's Water production.
(Feel free to add anything else, I will add more tomorrow. I don't have much time right now)