It seems there's a lot of people who think that images in Wikipedia
can be used however they like. In fact, unless they've been released
into the public domain, they have licenses that require some fairly
minor, but still important, actions if you want to use them.
Below is an email I've just sent to the owner of
Sydney
Architecture Images: Newtown Gallery, who seems to have taken all
the photos from the Wikipedia
article on Newtown, without any attribution, and slapped some ads
on it. I'm willing to give the person the benefit of the doubt.
Your Newtown Gallery is breaching the copyright of, it seems, all the
images from Wikipedia's Newtown article:
http://www.sydneyarchitecture.com/INW/MAIN-GAL-NEWTOWN.htm
Specifically, and what made me notice, is that you are using my photo:
Images on Wikipedia are not free for you to use without restriction,
unless specifically released into the public domain (for example, the
Trocadero image you've used). Most of the images on Wikipedia are
available under quite liberal licenses, but they do impose some
requirements on you.
In the case of my photo, I have licensed it under the GNU Free
Documentation License. This license has quite simple requirements,
basically that you must attribute the author and license your copy of
the work under the same license.
This image that you're using:
is licensed under a Creative Commons license, which has pretty similar
requirements.
So in summary, you are free to use these images, but only when you
follow the requirements of the license. Please amend your site
accordingly.