If you use Photoshop, as a rule when making photos black and white, instead of shooting them that way or simply desaturating them, I do it this way:
Image>Adjustments>Black & White and adjust the sliders to make the picture more interesting.. Your picture is a little washed out for my taste, so try this next time.
Or leave it color and do this: Image>Adjustments>Curves and play with that.. I usually start by making sort of an S-shaped line and working from there.. I'll bet you could get a really result with that cross in the foreground with this technique if you play with it a bit.
Another great thing to do, if you haven't already done it is to download Google's Picasa picture viewer... It's free, and it's very powerful. You can do things such as crop, saturate, sharpen, etc., and it does these things very nicely.