“Downtown” is not a thing abroad.
Americans, please stop saying that you stayed “downtown” when you travel abroad because downtown and uptown and sidetown and whatevertown are not concepts that exist abroad. You sound foolish and uneducated when you say you “stayed downtown” so just stop it already.
And if you just can’t help yourself from wanting to use the term downtown, then sub “city centre” for downtown. Examples: “We stayed in city centre” or “We stayed in the city centre”. Either works.