The Human species had become advanced enough to transform Coruscant into an ecumenopolis as early as a hundred thousand years prior to the Battle of Yavin. By 4000 BBY, Taris became one, having built itself up during the course of only a single century of prosperity; this world, however, still had its oceans, meaning only its landmasses had been completely built over.
One example of a lunar ecumenopolis was Nar Shaddaa, the largest moon that orbited the adopted homeworld of the Hutts, Nal Hutta. As far back as the Jedi Civil War and possibly long before, it had become entirely covered in kilometers-tall buildings, many of the lower areas of which had become quite decayed.
Ecumenopoleis in the galaxy
There were many ecumenopoleis within the galaxy, most notably:
Behind the scenes
"Ecumenopolis" comes from the Greek "οικουμένη" (oecumen) meaning "world," and "πόλις" (polis) meaning "city," thus translating to "world-city, a city made of the whole world." The term was coined in 1967 by the Greek city planner Constantinos Doxiadis. The term made its first appearance in a Star Wars source in Coruscant Nights I: Jedi Twilight.
The game Star Wars: Empire at War incorrectly depicts Corulag as an ecumenopolis; however, the only depiction of it as such is in its land map (which is a single cityscape), and that map may take place in the only large city on Corulag. Similarly, Kuat is described as covered in city-sprawl in Rules of Engagement: The Rebel SpecForce Handbook, though later sources have shown that the planet did in fact remain fairly free of urban sprawl, with the planet's industrialization being in the form of its massive orbital facilities.