Ghosts of DC offers this amazing 1880 map of property values in Washington, D.C. Adjusted for inflation, $1 in 1880 is worth almost $24 today.
One thing you see here are huge relative price shifts over time. Shaw and other mid-city neighborhoroods used to be much more expensive than Georgtown or Dupont Circle, perhaps because 19th century transportation technology put an enormous premium on proximity to the White House and downtown. You also see that, in general, urban land has appreciated considerably in price over the past 130 years. Even adjusting for inflation, these are basically bargain prices across the board.