Built to impress and terrify, the Tower was first a fortress in the 1070s and then evolved into a prison for enemies of the crown, including Anne Boleyn, the Nine Days' Queen, and Guy Fawkes.

It wasn’t clear what prompted the combining of the roles before 9:30 p.m. the evening of the crash, but this person said “not normal” was common phrasing inside the FAA and didn’t suggest ...