Under the clock

I'm told that, nowadays, when people say "meet me under the clock," they mean the clock in Grand Central Terminal.

But, apparently, 70 years ago it meant the clock in the Astor Hotel: The Clock.

The Clock (UK title Under the Clock) is a 1945 American romantic drama film starring Judy Garland and Robert Walker and directed by Garland's future husband, Vincente Minnelli. This was Garland's first dramatic role, as well as her first starring vehicle in which she did not sing.

I'm always fascinated by how expressions like that evolve and change while still retaining that essential meaning.