I see! That's not how I've taken 'Prime Minister' to be used, hence my surprise. It's used to refer not just to the person, but specifically them in that role for that time period.
So to me, President Obama was a (recent) historical figure, even though Mr. Obama is still alive.
I watched Top Secret! for like the third time. It's so funny! They don't make 'em like that any more. Unless they do: in which case, please tell me the title!
I guess scheduling for different days would be too difficult, but Saturday is the Jewish Sabbath (technically starting at night fall on Friday night) and Friday prayers are the most significant to Muslims.
I don't know if other religions have other special days.
I come from England but now I live in Western Canada. The oldest building is apparently a little wooden schoolhouse from the mid-1840s.
The likely oldest standing building in Canada is from 1637, a Jesuit mission house.