St Mary's Marylebone is a Grade I listed venue in central London offering distinctive conference and corporate event spaces. The Great Hall provides theatre-style seating for up to 600 delegates, featuring soaring ceilings, classical columns and natural light. The included Undercroft beneath the main hall offers flexible supporting space for registration, catering, networking, breakout sessions or workshops, and can be divided into two generous rooms plus three additional private spaces. Integrated sound systems support presentations and keynote speakers. Trestle tables are included; round tables available separately. External catering is welcome with a kitchen usage fee, or choose from recommended partners. Ideal for conferences, leadership summits, corporate gatherings and single-stream events.