Using examples taken from the text give me a list of the first generation of "skyscrapers" located in the city of Chicago.

Early Chicago Skyscrapers is a nomination comprising nine buildings in Chicago's Loop district for inclusion on UNESCO's World Heritage Site list.Submitted by the US Department of the Interior in 2017, it is currently on the tentative list considered for nomination as a UNESCO designated World Heritage Site. Only properties that have been previously listed on a tentative list can be nominated for the World Heritage List.

These buildings were constructed in the last 20 years of the 19th century and represent the first generation of "skyscrapers", high-rise structures reaching up to 20 stories. Construction of these buildings employed novel approaches and technologies, such as the use of steel frames, first elevators, electric lights, and terracotta fireproofing. The architects developed a new aesthetics for the exterior of this new type of buildings. The skyscrapers listed are the Auditorium Building, Second Leiter Building, Marquette Building, Rookery Building, Monadnock Building, Old Colony Building, Fisher Building, Schlesinger & Mayer Building, and Ludington Building.

Early Chicago Skyscrapers is a term which describes the nine buildings in the Loop district of Chicago, Illinois in the United States. These nine buildings were submitted by the US Department of the Interior in 2017 to be considered as a UNESCO designated World Heritage Site. These buildings are the Auditorium Building, Second Leiter Building, Marquette Building, Rookery Building, Monadnock Building, Old Colony Building, Fisher Building, Schlesinger & Mayer Building, and Ludington Building.