Original sentence: In the 19th century, the famed doctor Simon Baruch encouraged bringing European style spas to The States, and thus the Saratoga, with it's wealth of mineral waters developed as a spa, seeing many hotels built, including the colossal Grand Union Hotel that was in its day, the largest hotel in the world
Edited sentence: In the 19th century, the famed doctor Simon Baruch encouraged bringing European style spas to the US, and thus the Saratoga, with its wealth of mineral waters developed as a spa, seeing many hotels built, including the colossal Grand Union Hotel that was in its day, the largest hotel in the world