I saw a beautiful red brick structure across the river the other day.

Heh, good question, lol. I've always wondered about the meaning of across too.

A bridge across the river is not on the other side. This is the usual meaning.
A bank across the road is on the other side. This is the usual meaning.

But a brick structure across the river doesn't have a usual meaning, does it? I don't know. I think "across" is always ambiguous, but we usually as

This native thinks it's a red brick building on the other side of the river.

DelmobileThis native thinks it's a red brick building on the other side of the river.

Thanks, Kooyeen and Delmobile.

DelmobileThis native thinks it's a red brick building on the other side of the river.

This one does, too. If I wanted to say that I'd seen 'a structure that stretched from one side of the river to the other', well, actually, I might say it just that way, or I might say 'spanning the river', for example.

Yankee: « If I wanted to say that I'd seen 'a structure that stretched from one side of the river to the other', well, actually, I might say it just that way»

What about: "I saw a weird structure of rusty metal over the river?"

Hi Ant

I'd probably assume you had seen some sort of weird bridge-like structure (rather than a UFO, for example).

Thanks for reassuring me, Yankee!
Well, maybe a one-hundred-year old ufo?