Cunard is bringing Queen Mary 2, Queen Victoria, Queen Anne and Queen Elizabeth together to Liverpool on May 16.
https://www.cunard.com/en-gb/contact-us/media-centre/four-queens-celebration-announcement#
What a sight this will be! As a cruise enthusiast, especially Atlantic crossings, and a Liverpool enthusiast (4 trips so far), I think this would be amazing to see. Time to perhaps plan trip #5 to Liverpool!