drawing figure outside axis

Say I have drawn a plot and now I want to make an annotation on the top of the plot outside the axis. In my case I want to put a filled triangle up there in a certain location. I am using a polygon - patch to make the figure.

How does one do this? I have tried turning the clipping off but to no avail - I can put my triangle anywhere within the axis but if it is outside it disappears. In the manual there is an example for placing text outside the axis but not patches.

Thanks for any help.