Courtyard by Marriott Chicago Downtown/Magnificent Mile — Event Spaces & 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.
Floor plans
Detailed floor plans for Courtyard by Marriott Chicago Downtown/Magnificent Mile are published on the venue’s official site.
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Room capacities & dimensions
| Space | Sq ft / m² | Ceiling | Banquet | Theater | Classroom | Reception | Conference | U-Shape |
|---|---|---|---|---|---|---|---|---|
| Chicago BoardroomPlan this room → | 308 sq ft29 m² | 10 ft3 m | — | — | — | — | 14 | — |
| MichiganPlan this room → | 432 sq ft40 m² | 10 ft3 m | 30 | 48 | 25 | 40 | 20 | 15 |
| Ontario APlan this room → | 986 sq ft92 m² | 10 ft3 m | 80 | 105 | 64 | 99 | 35 | 30 |
| Ontario A & BPlan this room → | 1,870 sq ft174 m² | 10 ft3 m | 150 | 205 | 130 | 200 | 44 | 50 |
| Ontario BPlan this room → | 884 sq ft82 m² | 10 ft3 m | 70 | 90 | 56 | 89 | 30 | 25 |
| Ontario B & CPlan this room → | 1,632 sq ft152 m² | 10 ft3 m | 120 | 175 | 110 | 165 | 40 | 46 |
| Ontario BallroomPlan this room → | 2,618 sq ft243 m² | 10 ft3 m | 210 | 290 | 174 | 250 | 60 | 63 |
| Ontario CPlan this room → | 748 sq ft69 m² | 10 ft3 m | 60 | 83 | 50 | 79 | 25 | 20 |
| St. ClairPlan this room → | 308 sq ft29 m² | 10 ft3 m | — | — | — | — | 10 | — |
Figures from published venue data; blank cells mean the venue hasn’t published that number. Verify final counts with the venue.