held at vs held on

Some examples from the web:

• From 1991-2001, the event was held at Universal Studios Florida.
• An installation ritual was held at the Fairmont Hotel in San Francisco, California.
• On 29 August 2008, the 18th meeting of the external GP-B Science Advisory Committee was held at Stanford to report progress.
• Currently performances are held at TCU Place.
• Prêt-à-porter presentations are held at the showroom in Milan.
• It was held at the Autodromo Enzo e Dino Ferrari.
• The match was held at Athens Olympic Stadium.
• Later, regular sessions were held at Coudenberg in Brussels, Brabant.
• The presentation was held at Italian embassy in Moscow.
• And sometimes crochet classes are held at the library.
• He also confirmed that Vala was being held at that location.
• He's being held at the station, helping with our enquiry.
• A military wedding was held at Fort Russell.
• He's being held at New York Center.
• Some of the men were beaten and held at gunpoint.
• He's held at the Paju police station.
• Monday afternoon, a sailboat race will be held at the cesspool.
• You could be held at gunpoint, forced to say that.
• Sayid's being held at gunpoint.
• The service for Kielmeyer will be held at 1600 hours.

Some examples from the web:

• If only Stuart had held on a little longer.
• And she held on for another three years.
• And I held on to that anger.
• My subconscious has held on to everything.
• A tachograph CATP meeting was held on 26 June 2003 where these errors were reviewed and corrections were agreed.
• Early parliamentary elections were held on 11 May 2008.
• Meetings can also be held on specific issues.
• I've always held on to that table.
• A public hearing on radio was held on 24 May 2000.
• Somebody held on to her a while.
• Conciliation committee meetings on this issue were held on 23 April and 8 May, where an agreement was finally reached.
• The conciliation meeting was held on 4 June in Luxembourg.
• And the ATW crew is still being held on the plane.
• Two tripartite meetings were held on 28 February and 12 March.
• A further trialogue meeting was held on 22 January 2002 where a compromise package covering all outstanding issues was established.
• He was either held on the first floor and luckily made it out...
• A meeting with the complainant was held on 3 May 2000.
• A meeting with the French authorities was held on 20 October 2014 in Brussels.
• Such meetings shall be held on a mutually agreed date.
• The Convention's proposal regarding the weighting of votes must be held on to.