Alderaan, located in the Core Worlds, was a terrestrial planet covered with mountains and was known to the galaxy as “the planet of beauty”. Alderaan played a pivotal role in the establishment of the Rebel Alliance, a movement that sought to restore the Old Republic’s values.
What I'm enjoying about Obi-Wan Kenobi is that we are finally getting a sense of what was lost with the destruction of Alderaan.
Because the movies focus on Skywalker drama, the trauma and tragedy of its annihilation was never adequately addressed. Alderaan was more of an idea than a real place inhabited by characters we cared about. But now we get to see that, and it's devastating.
Leia had been silently living with that planet-sized grief and trauma for decades and only now is the magnitude of that being shown, ever so slightly, for what it is.