Relic World
Concept · Stellaris 4.5.2
Relic World in the Stellaris encyclopedia: - Base Habitability: 80%
Relic World in the game's words
The encyclopedia entry as the game shows it in its tooltips; underlined words open their own entry or page here.
- Base Habitability: 80%
- Can be restored by a Colony Decision, unlocking special 
Arcology Districts
A city once stretched across this entire world. Only ancient and abandoned ruins remain now, their original inhabitants long since departed.
Source: common/game_concepts (concept_pc_relic) and localisation/english, Stellaris Cygnus v4.5.2 (9776).