Architecture studio Jahn has completed a skyscraper in Chicago with two distinct sections, which is one of the last projects designed by studio founder Helmut Jahn.

Called 1000M, the 788-foot-tall skyscraper (223 metre) is located at the south end of the Michigan Avenue Historic District near the Chicago lakefront. It is one of the tallest residential skyscrapers in the city.

It has a distinct base with large, darkly coloured aluminium panels that are meant to reference the surrounding historic buildings while the top is set back slightly from the base and is more glossy – meant to complement the Chicago skyline.

"The deliberate change in form between the lower 19 floors and the tower above serves dual purposes," Jahn managing director Philip Castillo told Dezeen.

"The lower part of the building references the Historic Michigan Avenue District while the tower or skyline profile completes the towers at the south end of Grant Park complimenting the assembly of towers to the north."

The skyscraper was one of the last projects designed by studio founder Helmut Jahn, who died in 2021.

Originally the tower was meant to be condominiums, but in 2020, the plan was changed to contain rentable apartments, which brought the number of rooms up from 423 condominiums to 738 rental units.

According to Castillo, the top of the skyscraper was also "simplified" from the original design.

The first eight storeys are extended far into the block and the west side of this base structure holds parking with amenities including a pool on its top.

The skyscraper has a slight slope to the south, enabled because of the developer's purchase of an adjacent building, which gave the project air rights.

1000M's facades were curved in places to create different relationships with the distinct city typologies that the skyscraper faces.

"To make the tower above softer and thinner, the east and west fronts are slightly curved," said the studio.

"The hard-sloping edge of the northeast relates to the context of the city. The soft and natural corner to the southeast relates to Lake Michigan and Grant Park. The result is a rectangular plan at the lower floors that transitions to a parallelogram on the 72nd floor."

A "diagonal seam" runs up the north and south faces of the skyscraper, accentuating the slight taper of the tower.

Glazed curtainwall and milled aluminium spandrels characterise the tower facade, creating "omnidirectional" views for the apartments within.

"The basic idea was to transform a largely east-west oriented site for a building that had a north-south axis maximizing views to the lakefront, Museum Campus and Grant Park," said Castillo.

"The building slopes out approximately 12 feet at the northeast and southwest corners maximizing those opportunities and providing and iconic skyline image."

At ground level, a large structural truss can be seen through the curtainwall at the entrance. Residents can also enter through the doorway in the middle of the podium structure.

Interiors were designed in partnership with interior designer Kara Mann, and the accommodations range from studios to four-bedroom apartments.

Helmut Jahn was known for creating structures in Chicago, such as the Thompson Center, which was recently purchased from the city by tech giant Google, which will renovate it.

Pelli Clarke & Partners recently completed the 57-storey Salesforce Tower in Chicago's Loop in the centre of the city.

The photography is by Tom Rossiter.