I'm not sure if he can do that. I feel like eminent domain needs to be performed by a governor or federal. People need to remember that a Mayor isn't a "president of city that can do whatever he wants".

I'm pretty radical myself and I also just don't think it's necessary. There's more than enough unusued buildings to rebuild upon or renovate than a need to seize property. Even a place as dence as NYC still has a lot of land to utilize.