From the iStock thread about The Weltzeituhr in Alexanderplatz, http://www.istockphoto.com/forum_messages.php?threadid=332700&page=1, I found this Wikipedia link about Freedom of Panorama. http://en.wikipedia.org/wiki/Freedom_of_panorama

Inter alia, it says:
"Freedom of panorama, often abbreviated as FOP, is a provision in the copyright laws of various jurisdictions that permits taking photographs or video footage, or creating other images (such as paintings), of buildings and sometimes sculptures and other art which are permanently located in a public place, without infringing any copyright that may otherwise subsist in such works, and to publish such images. Panorama freedom statutes and/or case law limit the right of the copyright owner to take action for breach of copyright against the creators and distributors of such images. It is an exception to the normal rule that the copyright owner has the exclusive right to authorize the creation and distribution of derivative works. The phrase is derived from the German term Panoramafreiheit ("panorama freedom").
...
Laws around the world
Many countries have similar provisions restricting the scope of copyright law in order to explicitly permit photographs involving scenes of public places or scenes photographed from public places. Other countries, though, differ widely in their interpretation of the principle.

In the European Union, Directive 2001/29/EC provides for the possibility of member states having a freedom of panorama clause in their copyright laws, but does not require such a rule.

Panoramafreiheit is defined in article 59 of the German Urheberrechtsgesetz, in article 27 of the Swiss Urheberrechtsgesetz, in section 62 of the United Kingdom Copyright, Designs and Patents Act 1988, and it exists in several other countries.

On the other hand, there are also European countries such as Italy, where there is still no freedom of panorama at all. In Italy, despite many official protests and a national initiative led by the lawyer Guido Scorza and the journalist Luca Spinelli (who highlighted the issue), the publishing of photographic reproductions of public places is still prohibited, in accordance with the old Italian copyright laws.

<snip>

Anyone know about this Italian legal let-out? There are many 'out and about' ancient buildings photos (a very few of them mine) in Italy in iStock's main collection, and we know how they tend to 'err on the side of caution'. I'm going to Florence in a couple of months and should have some photo time. I'm guessing there's more to it than the last paragraph above.

Thanks all. I wasn't really worried about taking the photos - I'm good at 'acting the tourist' - it was selling them that was giving me pause.

This is an interesting topic. I wasn't aware that photographing monuments from public places isn't permitted in Italy. I just took a gander on IS and there are probably thousands of images of Italian monuments - many weren't even taken from public areas (e.g. shots clearly taken from inside the Colosseum). I can't imagine there's much money to be made with all the similar images already online.