Reader thisisbossi created a fantasy Metro map with a LOT of lines:

He writes,

Yes, this is an absolute pipedream… hence the [title “DC 2100”]. While I laid these out to be at least somewhat technically feasible, everything shown would still require immense amounts of funding, right-of-way, and political will.

That’s true, though this map also brings to mind another heavy rail system that does exist:

Paris has more lines than even thisisbossi’s map, and in a smaller space, too. It’s just that there, the political will exists to build some of the best transit in the world in a nation’s capital city, while here, at least a significant part of one major political party would spend absolutely nothing on transit or the capital city.