They're definitely worth some time to wander through. A few items of note:

* In 1909, the northern third of the Canal Park site between I and K was nothing more than a passage to the rail yards where 70 and 100 I now stand. You can also see the streetcar line that used to run along K Street east from Second. Then there's the Washington Fertilizer Company that used to sit at New Jersey and K--maybe the defunct trash transfer station isn't so bad in comparison? And the Van Ness school used to be on the west side of Fourth at M, where 300 M and Sizzling Express now are. (The newer school opened in 1956.) And this same 1909 map shows that Exxon has been on the unit block of I Street for a LONG time, with Standard Oil occupying the eastern two-thirds of the block--it would spread to the entire block by 1921.

* In 1903, the Navy Yard ran only from Sixth Street to Ninth. (You'll also see that Potomac Avenue used to be named Georgia Avenue.) By 1909 it had expanded west to Fourth Street. In 1921, with World War I over, its western border had moved to New Jersey Avenue. (Alas, the Navy Yard plate for 1921 isn't posted--no doubt the Homeland Security department of the era asked for it to be removed since it was a potential aid to terrorists.)

* There was a St. Matthew's Chapel on the southeast corner of Half and M (where most everyone now exits the subway to head to Nationals Park), which I imagine is the forebear of the St. Matthew's now at New Jersey and L.

* The American Ice Company used to operate at a wharf at Second Street and the Anacostia River (which used to just be called the Eastern Branch). This is where the "Great Lawn" of the Waterfront Park at the Yards will be. Plus, Florida Rock and the southern half of what's now the WASA site didn't exist in 1903, but by 1909 the land had started to be reclaimed and you can see the "Sewer Dep't." Plus. the beautiful WASA main pumping station is depicted, having been built in 1905.

* When they call the Maritime Plaza site at 12th and M "the old Washington Gas site," they're not kidding--there it is in 1903, marked as the Washington Gaslight Company.

* The park at Ninth and Virginia has been there since at least 1903, when it used to be the meeting place of Virginia and Georgia avenues (and when there wasn't a big freeway above it). On the same map, you can see the previous life of the Blue Castle at Eighth and M, marked as the Washington & Georgetown R.R. Co. Car House. (It didn't take up the entire block then.)

So, go to the main map page, and pick a year and a plate, and take a trip back a hundred years or so. And also check the few Historic Photos I've found over the years, too.