The most striking thing about bicycles in
the Capitol is that there really is something for everyone, the bicycles don't fall into one tribe. I found the diversity refreshing.
From the fixed gear in
Dupont Circle:

The symphony in blue and purple on the
National Mall:

A hybrid with a seat shaped like a cow near the Embassies:

A luscious purple cruiser in Georgetown:

Tricycle parking in
Georgetown:

and and unrelated Mama Chariot in Georgetown:

A basket bike in Dupont Circle:

Raleigh 3 speed in Dupont Circle (with a nicely attached modern tail light):

A
pennyfarthing at the
Smithsonian:

And my favorite, a singlespeed designed and manufactured by the
Wright Brothers, which helped to finance their dabblings in aviation.