Number One City Datum

This bench mark designates the primary datum for the City of Chicago. It is from this point that all heights in the city are measured.

"The City Datum is hereby established as a plane 17.640 feet below the bench mark cut on top of the bottom stone of the granite base at the southeast corner of the Northern Trust Company Bank Building at the northwest corner of S. LaSalle Street and W. Monroe Street."

September 12, 1928                                                                                                            Municipal Code of Chicago

Submitted by: Stephen Sostaric