By the time Vaughn thought about bringing humanity back to Veldanyr, over 70,000 years had already passed since the end of the Great Cataclysm.
During those 70,000 years, it went without saying that a lot of things had changed on Veldanyr aside from Vaughn.
One of those changes were the many buildings that used to house Veldanyr's humanity in the past.
Due to the inevitable passage of time, many of the buildings beyond the capital city in the past had already eroded.
Partly, it was due to nature's tenacity to reclaim what it rightfully owned.
Mostly, it was due to the Myth-level strength Vaughn was unleashing during the majority of those 70,000 years, the shockwaves his attacks sent out gradually reducing the rigidity of the buildings.