Below are major hotels in Sri Lanka known for large, purpose-built convention / ballroom facilities (useful for conferences, exhibitions, large banquets). I list the venue, location, typical capacity/strengths and one source you can check for floor plans and current capacities.

• Shangri‑La, Colombo (Colombo) — very large ballrooms and divisible function rooms; combined ballroom capacity reported up to around 1,500–2,000+ depending on configuration (commonly used for large international conferences and gala dinners). (en.wikipedia.org)

• Cinnamon Grand Colombo (Colombo) — long-established downtown hotel with multiple ballrooms (Oak Room, Atrium, etc.) and many breakout rooms; main ballroom(s) support conferences and banquets for several hundred to ~1,000+. Good for large multi‑room events. (oxfordbusinessgroup.com)

• Cinnamon Lakeside / Cinnamon Life (Colombo) — Cinnamon Lakeside has large meeting rooms/ballrooms (100–450 capacities in rooms listed); the Cinnamon Life integrated resort complex also advertises very large MICE/exhibition space (suitable for large conventions/exhibitions). Check Cinnamon Life for the largest exhibition/ballroom options. (oxfordbusinessgroup.com)

• Hilton Colombo (Colombo) — hotel ballrooms and pillar‑free meeting spaces suitable for large conferences and banquets (ballrooms reported in the mid‑hundreds to ~1,100 depending on configuration). Good AV and central location. (brandradar.org)

• Taj Samudra (Colombo) — waterfront hotel with large ballrooms, marquees and lawns used for big banquets and conferences; flexible indoor/outdoor event space for several hundred to 1,000+ depending on setup. (brandradar.org)

• The Kingsbury / Galadari Hotel (Colombo) — harbour‑front hotels with large, flexible meeting rooms and ballrooms commonly used for mid‑to‑large conferences and exhibitions. (brandradar.org)

• Waters Edge (Battaramulla, near Colombo) — a major hotel/conference complex with large dedicated halls and exhibition facilities used for corporate and government conferences (often used when large contiguous exhibition space is required). (nkarmice.com)

• Heritance Kandalama (Dambulla area) — resort with large meeting spaces for up to a few hundred (popular for conference retreats in the Cultural Triangle). Not as large as Colombo city ballrooms but excellent for mid‑sized conferences and incentive events. (nkarmice.com)

Notes and suggestions

• If you need exact capacities, floor plans, AV specs or block‑room availability for specific dates, ask me which city/approximate attendance you expect and I can pull exact current capacities and contact/booking pages for each venue. (Capacities and room names/configurations change — always confirm directly with the hotel event sales team.) (en.wikipedia.org)

If you’d like, I can:

• Narrow this to Colombo-only venues and provide ballroom names + exact capacities and links; or
• Suggest non‑hotel convention centres (BMICH, SLECC, Hambantota International Convention Centre) if you need very large contiguous exhibition halls.