Otoh Gunga (Earth-2356)

Otoh Gunga is a Gungan city located beneath the surface of Lake Paonga on the world of Naboo. Its bubble-like buildings are in fact hydrostatic force fields that contain breathable atmospheres for their occupiers, and have special portals that allowed its inhabitants to enter and exit. Since the Gungans actually grew the building material of their cities from the natural plasma of Naboo and bubble wort extract, the structure of Otoh Gunga is a hub and spoke network. The city notably house the Gungan High Council, which rule over the Gungans from the High Board Room. The city was originally built by the Gungans in order to avoid contact with their surface-dwelling Nabooan Human neighbors.

History
When the Trade Federation invaded Naboo, their armies stormed the swamps, forcing the Gungans to abandon Otoh Gunga.

Source

 * https://starwars.fandom.com/wiki/Otoh_Gunga.