Nilopolis or Delas was a city in Egypt situated on the left bank of the Nile, about forty-seven miles from Memphis. It was an episcopal see that a suffragan of the metropolitan of Oxyrynchos, in the Roman province of Arcadia Aegypti, and is included as such in the Catholic Church's list of titular sees.

Nilópolis is a municipality in Brazil, located in the Rio de Janeiro state's southwestern region, bordering São João de Meriti, Mesquita and Rio de Janeiro. It is the smallest municipality in Rio de Janeiro state, with a total area of 19.39 km². The population of 157,483 inhabitants living in an area of 9 km² and the remaining area corresponds to the Gericinó's Natural Park. Officially, the population density exceeds 8,120 inhabitants/km², but if calculated just 9 km² occupied, it becomes the most densely populated city in Brazil with more than 17.400 inhabitants/km². Currently, São João de Meriti has the highest population density, with 12,897 inhabitants/km².