Alderaan

Alderaan was the conscience of the Core: a temperate world of snow-capped mountains, glacial lakes and grass oceans whose civilization prized art, philosophy and diplomacy over arms. Its cities, like the capital Aldera, were built to blend into the landscape, and after the Clone Wars the planet formally disarmed - keeping its weapons aboard an armory ship rather than on its soil.

In 0 BBY Grand Moff Tarkin chose Alderaan, home of the openly rebellious House Organa, as the demonstration target for the Death Star. Its destruction - two billion lives - was meant to terrify the galaxy into obedience; instead it lit the fire of open rebellion. The debris field is now called the Graveyard, where survivors ('Alderaanians abroad' who happened to be off-world) return to leave offerings.