Thanks for getting back to me.
Google Images allows you to search the internet for pictures that
match your search terms. The main search page is here:
I conducted a search on:
"world trade center" OR wtc site:gov
which returns over 1,000 images of (or related to) the World Trade
Center exclusively from websites that end in the .gov extension --
that is, from government websites.
Note that not all these sites are FEDERAL sites...I would suggest
looking for pictures only from sites belonging to federal government
agencies, as their rules pertaining to copyright are clearer than
state or local government sites.
In general, pictures on federal websites that are not identified as
originating from a non-government source, or are not indicated as
copyright-protected, should be in the public domain.
However, in the crush of events surrounding 9/11, I'm not certain all
sites followed their own quidelines for posting pictures. I would
advise some checking around before assuming a picture is public
I've always found this NASA picture particularly compelling:
and it is definitely in the public domain.
Let me know if you need additional help on a picture or two, and best
of luck with your presentation.