system
Given the following post, respond as if you're commenting on Reddit:
human
[General] How long does it take to build an ecumenopolis?

In sci-fi, we see plenty of examples of city planets, such as Coruscant and Trantor. How long would it take to build one of these planet-wide cities?
gpt
Safe to say that these worlds generally take more than a regular human lifetime, usually at least centuries. This is hugely dependent on a number of different factors, however. Coruscant for example didn't start as an ecumenopolis, it started as a regular planet but over millennia built up to the world we see in the prequels, as levels kept getting added and the natural ground disappeared beneath the foundations of the megastructures.