Memorial Bridge connects DC's monumental core to Arlington National Cemetery in Virginia. It's not a particularly important road connection, because it's not a highway and there are parks at either end. But it is one of the two really important pedestrian/bike river crossings (along with the Key Bridge), because there's a Metro station immediately on the Virginia shore, and because there are important regional bike trails on both sides.
Also, people like it just because it's pretty. Walking across the bridge is part of the park experience of being on the National Mall.
So here are some pictures of the bridge, and the approach from DC. BTW, these pictures are a couple of months old, which accounts for the bare trees.
This is Rosslyn VA. The building you see under construction has since been topped out, and at just a touch below 400' is now officially the tallest building in the DC region besides the Washington Monument. It won't be for long, though. A slightly taller building is going up right across the street, and one that will actually breach the 400' barrier is proposed in Tysons Corner.
The DC side of the bridge is a large traffic circle. Really it's a circle-shaped city block. The Lincoln Memorial sits inside the circle, and along the waterfront there's a set of steps, called the Watergate Steps. They predate the Watergate building complex, made famous by Nixon.
There are actually 2 bridges that meet at the circle. The other crosses over Rock Creek.
OK. Let's cross.
This is looking upstream towards Georgetown. The bridge you see in this pictures is the Roosevelt Bridge, which carries I-66 and US-50. The building with the spires is part of Georgetown University.
This is National Cathedral, a couple of miles inland from Georgetown. The waterfront buildings are in Georgetown.
Looking the same direction, just panned further to the left.
Approaching the other shore, you can see the Mount Vernon Trail and George Washington Memorial Parkway.
There's another circle on the other side of the bridge. Most people think of this as Virginia, but technically speaking it is still DC. At this point you're actually on an island in the river, not the mainland. To cross into Virginia you have to go over another short bridge, called the Esplanade.
At the far side is Arlington National Cemetery, and its Metro station.