There is a certain amount of randomness about which museums and memorials are on the National Mall. And, for the foreseeable future, there has to be such randomness. There wasn’t a master plan set up in the early nineteenth century which dictated that over the next two centuries memorials and museums would be built in a given order. Every couple of decades, someone lobbies Congress hard enough that a new memorial or museum is built there. Every time this lobbying succeeds, there’s less prime space available.
It’s going to get harder and harder in the future for such things to be built on the Mall. As it is, the Mall is presently in about as classically elegant state as it ever has been. The ugly temporary buildings on the Mall were finally torn down in the 1960’s. Good spaces for new museums and memorials are farther from the Mall than ever. For those of you who wonder why your favorite possibility for a museum or memorial isn’t being built on the Mall, it’s because there isn’t room. If they start filling up the long rectangular grass area on the Mall, the area will truly look ugly. If your lobbying group is convinced that there’s a need for a new museum or memorial, please put in somewhere else in Washington than on the Mall. Or why not put it in some other city?