Dienstag vergangener Woche in Monaco.
Is that the same as Letzten Dienstag?
Am Dienstag vergangener Woche
on the Thursday of last week. While
am letzten Dienstag
last Thursday. They're very similar but not the same.
They mean the same on Mondays and Tuesdays but not so on the other days.
Dienstag vergangener Woche is the same as Dienstag letzter Woche
Last week's tuesday
both should not be confused with Letzten Dienstag
Pay attention, that a German week starts on Monday, not Sunday. So a sentence like Sunday last week might refer to yesterday if said no a Monday.