Washington DC as the nation's capitol is home to embassies and consulates from countries around the globe. In addition a number of global entities call Washington DC home. Washington DC is truly multi-ethnic and you can find representatives from all nationalities, all skin colors in DC.
Yes, in fact there are many different rail lines. Amtrak trains pass through Washington DC and Virginia. The Washington DC Metro system has many stations in both Virginia and Washington DC. CSX and other cargo trains pass through DC and Virginia.
Much of the property in DC is owned by the Federal government. Other property is owned by various foreign embassies. Most of the rest is owned by the same folks one would find as owners of property in any other town: local government, private businesses, private residents, etc.
Washington - Baltimore Washington International, DC, USA (BWI) Washington - Washington - All Airports, DC, USA (WAS) Washington - Ronald Reagan National Airport, DC, USA (DCA) Washington - Washington Dulles, DC, USA (IAD)