ChicagoChicago's street raisingLifting a whole downtown with hand screws is a huge job. Was raising the buildings easier than digging them out, or was something already covering the old street?In the 1850s and 1860s central Chicago was raised to a new grade. Buildings were lifted on jackscrews, and in January 1858 a four-storey, 750-ton brick building at Randolph and Dearborn went up 6 ft 2 in.
Photo: Jean-Pierre Dalbéra from Paris, France · CC BY 2.0 · via Wikimedia Commons
Mud Flood · Paris, France
Notre-Dame archaeological crypt
The open question
Paris sits on top of older Paris. How many metres of city are under the cathedral square?
On the record
Under the square in front of Notre-Dame, a crypt shows old streets, quays and foundations from Roman times on.
Sources
More from Mud Flood
ChicagoChicago's street raisingLifting a whole downtown with hand screws is a huge job. Was raising the buildings easier than digging them out, or was something already covering the old street?In the 1850s and 1860s central Chicago was raised to a new grade. Buildings were lifted on jackscrews, and in January 1858 a four-storey, 750-ton brick building at Randolph and Dearborn went up 6 ft 2 in.
ChicagoTremont House hotel liftWhy lift a big brick hotel rather than just fill in around it?In 1861 Ely, Smith and Pullman lifted the Tremont House hotel six feet to meet the new street grade.
SeattleSeattle UndergroundA whole storey of shops ended up below the street. Why build new streets a floor up instead of on the old ones?After the 1889 fire, Pioneer Square's streets were raised from several feet to a full storey. The old sidewalks and shopfronts are still down there, lit by glass vault lights. The city condemned the Underground in 1907.
SeattlePioneer Building, SeattleIf the old ground floor is underground, which floor was really the first one?Built in Pioneer Square after the 1889 fire; Bill Speidel's Underground Tour has run from it since 1965.