The Dragon's Hoard

Tyralgarde the Invincible, like many other dragons before him, accumulated incredible troves of wealth over millenia. Within this hoard were magical artifacts from forgotten kingdoms, crowns from long-dead kings, and piles of gold coins sniped from unlucky caravans on the Gold Road.
Once slain, The Golden Dawn honored the memory of Bolivar Castore by allowing his family to collect the vast majority of the wealth.
This windfall of money allowed Selgaunt, led by Cynthia Castore, to invest in its future. Lady Castore invested heavily in magic, and bought the services of countless magi. With them, she found new mines of precious metals, built magical colleges, and re-carved a sliver of the Sea of Fallen Stars to allow safe passage by ship where it was previously impossible. This led to more wealth, which she used to construct new forts and sponsor initiatives to rebuild the towns of her kingdom.
Today, Selgaunt is the economic engine of Sembia, and the only city left with the power to rival Selgaunt.