Number One City Datum - Chicago, IL - U.S. Historic Survey Stones and Monuments on Waymarking.com

The city datum is...a plane 17.640 feet below the bench mark cut on top of the bottom stone of granite base... Sept 12, 1928.

In 1905, construction began on the new Northern Trust building, built of granite, marble and other materials that would last. Strong concrete pillars reached down to bedrock, 105 feet below street level, to carry the heavy structure above. Years later, city engineers, saying that they considered the building sag-proof, cut into Northern's cornerstone a bench mark known as the Number One City Datum Mark, From this mark the heights of all future structures in Chicago would be measured.

50 South LaSalle was also hailed as the first totally air conditioned building in the City in 1929.

Monumentation Type: other (not included below) Monumentation Type (if other): wall mounted plaque Monument Category: other (not included below) Monument Category (if other): datum Accessible to general public: yes Monument Website: [Web Link] County: Cook County, IL Approximate date of monument: 09/12/1928 Explain Non-Public access: Not listed Historical significance: Not listed USGS Quad: Not listed NGS PID: Not listed Other Coordinates: Not Listed Other Coordinates details: Not listed

Visit Instructions:
1. A closeup photo of the monument is required.
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2. A 'distant' photo including the monument in the view is highly recommended. Include the compass direction you faced when you took the picture.

Recent Visits/Logs:

Date Logged Log User Rating   10/20/2014 Go Boilers! visited it