This is sort of an odd picture. It's the Washington Monument, of course, but it doesn't really look very tall. Is it because of the trees, which distort our sense of scale? Or about shooting it from slightly above its base? Or about the cropping of the photo? I'm not sure.

Welcome to the woman's point of view, Kevin.
Like +15!
It's because depth perception is lost in silhouettes. You can't tell whether the trees are right in front of the monument, or much closer to you.
I hear trimming can make it look more impressive.
Basically what Ken wrote.
Looks like the same thing that photobombs all of the Paris pictures…
lens used?
It's the result of two things:
(1) Barrel distortion from using an ultra-wide lens.
(2) Extreme underexposure decontextualizing the details that make foreground details appear closer in distance to background, thus affecting scale.
I guess it shows that Washington didn't wax.
+10
Simple: `tis good.
If you wanted "tall", you should have photographed the Clinton Monument, right next to it.