Before revision: Many of the city's old wooden buildings were considered unworthy of the prime plots of land whereon they stood, and so instead of raising them, the owners of these wooden buildings had them either demolished or else placed on rollers and moved to the outskirts of Chicago.
After revision: Many of the city's old wooden buildings were considered not worth raising, so instead the owners of these wooden buildings had them either demolished or else placed on rollers and moved to the outskirts of Chicago.