Signs of urban expansion appeared in the early 19th century, when three large, innovative, and internationally recognized institutions were located in the district. The first of these was the Fairmount Dam and Water Works at the foot of Fairmount Hill. Beginning in 1822, the Water Works used waterpower to pump water from the Schuylkill River into reservoirs on the top of Fairmount Hill, from where it flowed by gravity into city homes and businesses. An engineering wonder, it was also an architectural and scenic attraction. Its buildings, which included a restaurant, are among the earliest examples of Greek Revival architecture in the United States. Protection of the municipal drinking water that the Water Works pumped was the impetus for the purchase of lands along the Schuylkill that later became Fairmount Park, one of the world's largest municipal park systems. Charles Dickens listed the Water Works as one of the two things he particularly wanted to see while in Philadelphia.