Jonathan's method will work fine ... but it might be tricky to get the colour adjustment exactly right. The colour sampler tool will help, but still it might be tedious to get right.
So here's another method which may or may not work better than Jonathan's ... just give it a try.
Carefully select the offending window using your preferred method---e. g. lasso, polygonal lasso, or magic wand. Selecting a window from a building's facade should be a fairly easy job (unlike selecting a person's head with fly-away hair, for instance). Put the selected part of the image onto a separate layer through hitting Ctrl-J (Cmd-J on the Mac). Do not select much of the surrounding wall; only select the part that you actually want to have the colour adjusted.
Go back to the background layer and do the same with another window; select it in the same way you did with the first window. Now you're supposed to have the background layer, one layer with the offending window, and one layer with one of the well-coloured windows.
Now click on the layer with the offending window to make it the active layer, then select Image > Adjustments > Match Color. In the lower part of the dialog, select the layer with the single fine window as the source, hit OK, and you're done.
-- Olaf