How to plot a rectangle on a map

I'm embarrassed to ask this but...

I want to plot a rectangle on an (x,y) map. 

It's just a simple rectangular outline. Not an image, or an
x->y function, or a colour shaded terrain map or anything
clever.

I need to be able to specify its size and rotation from
vertical but that's it.

It seems to be an incredibly simple task and I'm sure there
must be a simple way to do it but looking through the
tutorials and documentation I just can't find one.

Would be indebted if someone can show me the 2 line solution.

Andrew

______________________________________________________________________
BG Energy Holdings Limited (a member of BG Group)
Registered in England No: 3763515
Registered Address:
                        100 Thames Valley Park Drive
                        Reading
                        Berkshire   RG6 1PT   UK
Telephone:              +44 (0) 118 935 3222
Website:                http://www.BG-Group.com

This e-mail is intended only for the addressee named above.  As this 
e-mail may contain confidential or privileged information, please 
advise us immediately if you are not the named addressee or the person 
responsible for delivering the message to the named addressee.  The 
contents should not be disclosed to any other person nor copies taken.
______________________________________________________________________