Me? Oh.. yes. Right.
Well. Infrastructure. There must be infrastructure also known as services like water, trash removal, vermin control, roads, mail, etc. Codified laws and the means to enforce them. A belief system, a communicated, shared belief system (also known as culture). Written language. Not necessarily an alphabetical one like ours, but even a symbolic one like ancient Egypt or pre-conquest Meso America. History. A civilization must have a history to justify itself with. Trade. People specialize and produce or provide one thing and trade it for other things they need. This allows expertise to develop allowing people to become excellent at one thing rather than spending all their time merely subsisting.
There's more, I'm sure.
Civilizations end. As ours will eventually. The trick to sustaining one, however, is to convince the population that this will never happen. But Mr. Average Roman and/or Mrs. Average Aztec also believed their world would go on forever, too.