I did some cleanup in OpenStreetMap, around the National Mall in DC. Some parks data from DCGIS had been imported, but there were duplicates with what was already in OSM. In looking at the map after my cleanup, I noticed something quite odd. "Vietnam Memorial" is written with the "memorial" part upside down. I didn't realize that Mapnik writes labels upside down.
In edit mode, I saw that the Vietnam Memorial was drawn as a polygon and tagged with just a name. Also, the Constitution Avenue label is cut off and shows it as just "Constitu". I went in and tagged the Vietnam Memorial as tourism=attraction and historic=memorial. Now it renders as an area and seems labeled properly, offset from the polygon and right side up.
Though I am not sure the walkways are correct and need to check them with a visit. There is plenty more to do with both data imports and collecting details around the mall.