Courtyard by Marriott Chicago Downtown/Magnificent Mile — Event Spaces, Floor Plans & Capacities

165 E Ontario St, Chicago, IL 60611

Courtyard by Marriott Chicago Downtown/Magnificent Mile gives Chicago event planners 9 spaces to work with across 9,786 sq ft909 m² of function space. The largest room, Ontario Ballroom, hosts up to 290 guests. Review the layouts and seating capacities below, then test your setup in 3D — free.

Across its 9 spaces, Courtyard by Marriott Chicago Downtown/Magnificent Mile handles theater-style sessions for up to 290, seated banquets for 210 and standing receptions for 250. 3 smaller rooms suit breakouts and board meetings. Exact figures for every room and setup style are in the chart below.

Plan your event in this space — free

Floor plans

Detailed floor plans for Courtyard by Marriott Chicago Downtown/Magnificent Mile are published on the venue’s official site.

View official floor plans at Marriott ↗Plan your event in this space — free

Work at this venue? to publish your official floor plans and 360° tours here — free.

Room capacities & dimensions

Room capacities and dimensions for Courtyard by Marriott Chicago Downtown/Magnificent Mile
SpaceSq ft / m²CeilingBanquetTheaterClassroomReceptionConferenceU-Shape
Chicago BoardroomPlan this room →308 sq ft29 m²10 ft3 m————14—
MichiganPlan this room →432 sq ft40 m²10 ft3 m304825402015
Ontario APlan this room →986 sq ft92 m²10 ft3 m8010564993530
Ontario A & BPlan this room →1,870 sq ft174 m²10 ft3 m1502051302004450
Ontario BPlan this room →884 sq ft82 m²10 ft3 m709056893025
Ontario B & CPlan this room →1,632 sq ft152 m²10 ft3 m1201751101654046
Ontario BallroomPlan this room →2,618 sq ft243 m²10 ft3 m2102901742506063
Ontario CPlan this room →748 sq ft69 m²10 ft3 m608350792520
St. ClairPlan this room →308 sq ft29 m²10 ft3 m————10—

Figures from published venue data; blank cells mean the venue hasn’t published that number. Verify final counts with the venue.

Frequently asked questions

How many event spaces does Courtyard by Marriott Chicago Downtown/Magnificent Mile have?
Courtyard by Marriott Chicago Downtown/Magnificent Mile has 9 event spaces totaling 9,786 sq ft.
What is the largest event space at Courtyard by Marriott Chicago Downtown/Magnificent Mile?
The largest event space at Courtyard by Marriott Chicago Downtown/Magnificent Mile is Ontario Ballroom, which holds up to 290 guests across 2,618 sq ft.
What is the banquet capacity of Ontario Ballroom at Courtyard by Marriott Chicago Downtown/Magnificent Mile?
Ontario Ballroom seats up to 210 guests in a banquet layout.
How many people fit in Ontario Ballroom theater-style?
Ontario Ballroom holds up to 290 guests in a theater setup.
What are the dimensions of Ontario Ballroom?
Ontario Ballroom measures 77 × 34 ft (2,618 sq ft) with 10 ft ceilings.

More event venues near Chicago

Other event venues in Chicago, IL

Event venues elsewhere in Illinois

Venues with similar capacity (~290 guests)