[Roger Slater]

You can speak off the top of your head, or you can look it up. In the US, and I suspect this mirrors most other jurisdictions,

(a) Pictorial Representations Permitted.— The copyright in an architectural work that has been constructed does not include the right to prevent the making, distributing, or public display of pictures, paintings, photographs, or other pictorial representations of the work, if the building in which the work is embodied is located in or ordinarily visible from a public place.

17 USC Section 120.

Note that this "photographer's exception," as it's sometimes called, does not apply only to the taking of a photograph, but to the distribution or public display of the photograph, which would allow such things as use on a book cover.

It's a dicier question when it comes to public art, such as a sculpture, and I don't know the answer for sure, but I suspect that the answer is that it's okay if the art is included in the scene you are photographing, but not okay if the photograph is primarily about showing the art work. (I just noticed Wintaka's link, which apparently answers the question, at least for the UK, by indicating that it's not an infringement to draw or photograph public art. The US statute, by contrast, refers only to buildings, not to art. Still, without looking it up and nailing it down, I would be shocked if it were illegal to take and sell a picture of a public square because you can make out on a single corner a small statue that is under copyright, or if there were a billboard in the background with copyrighted advertising text, or someone wrote and owns the copyright to graffiti painted onto the side of a subway car that happens to be passing by.).