With only a three hour layover, and presuming flights are on time....Is there time to take a cab into the city and drive around to see the monuments, etc?

I don't think so.

I would say not.

I think u could have about an hour or so to kill. DCA is a small airport and generally security lines are not too bad. What time do u arrive and what time does your outbound flight depart? Its about 15-20 minutes drive each way into the city and you'd have about an hour to drive around. Is that what u wanted to do, just do a drive by? Not a lot of time to really see alot, but doable.

If your layover is anywhere remotely close to the afternoon traffic rush I wouldn't do it. But if it's really off peak or on a weekend you could give it a go.

Arlington Cemetery and Iwo Jima and Netherlands Carillion are on the same side of the river as the aiport. Great views of the city from Iwo Jima.

Thanks! These are the responses I needed! I will figure it out from here.