Equitable Building

The Equitable Building is an International Style skyscraper designed by Skidmore, Owings & Merrill, with Bruce Graham, Natalie de Blois as lead architect, and built between 1963 and 1965 in Chicago, IL.

Equitable Building is not the only name you might know this building by though. The building is, or has also been known as 401 North Michigan.

Its precise street address is 401 North Michigan Avenue, Chicago, IL. You can also find it on the map here.

At the time of the sale of the land owned by the Chicago Tribune, it was stipulated that the new building should have a plaza along Michigan Avenue to preserve the view of the Tribune Tower and the Chicago River. This plaza is now known today as Pioneer Court.

The Equitable Building embraces the international-style skyscraper that Mies, who at the time had a thriving career in Chicago and across the US, had envision and executed for the Seagram Building in NY before the Equitable Building, and much closer a few years later in 1970, just a couple blocks away, at the IBM Building.

Skidmore, Owings & Merrill, with Bruce Graham, Natalie de Blois as the lead architect, was the architecture firm in charge of the architectural design.

That being said, architecture is a complex discipline involving many professionals from different fields, without whom this building would have not been possible. We will surely be leaving out a lot of names here, but at the very least we know that there was one other part involved, that was Equitable Insurance Company as the Main Developer.

The Equitable Building can be categorized as an International Style building.

The Equitable Building was completed in 1965. By 1965 the International Style movement had already left its early days behind and could be considered a mature movement, which does not mean it was loved and accepted by everyone, on the contrary. The International Style was accepted by the architecture community way before it was by the general public, and it is therefore likely that the Equitable Building was not well received by everyone at the time.

The Equitable Building uses a framed tube-in-tube structure , with steel columns and concrete slabs.

A framed tube-in-tube structure uses a central core, known as inner tube, which usually holds stairs, lifts and installations, and a perimeter of columns around it, which form the exterior tube. The interior tube is tipically more massive (often made of reinforced concrete), and the exterior tube is "lighter" (made of steel or concrete columns). Both tubes are conencted via horizontal elements which make up the floors and also transmit any horizontal froces from the facade to the core.

The facade of the building is load bearing. This is a direct consequence of the integration of the exterior "tube" into the facade, something which most framed tube-in-tube buildings do in order to liberate the interior space from structural elements and achieve a more flexible interior.

So the facade of the builing is techinically load-bearing, yes, however, in between the load-bearing colums we find a curtain-wall type of facade, which by itself would not be cosnidered load-bearing.

From an aesthetic point of view, the facade features an open ground floor, continued by a dark curtain wall.

The curtain wall is organized in 3 bays on the short side of the floorplan and 5 bays on the long side, which are determined by the structural pillars embedded into it. In each bay, bronze-tinted glass and aluminum spandrels, together with the style characteristic column coverings and vertical mullions create a repetitive rhythm both horizontally and verically.