If you can't trust a city street sign to tell you where you are, what -- or who -- can you trust? Well, one thing is sure: You can't trust the street sign pictured above to tell you where you are, and, gee whiz, you're one block from the White House.

To set the scene, as the sign indicates, you're at H Street and Jackson Place NW, at the northwest corner of Lafayette Park. That means that, contrary to the smaller print on the H Street sign, you are most definitely not in the 1700 block of H Street. You're in the 1600 block. The 1700 block begins one block to the west -- that is, to the right of the sign as you're viewing it here.

You'd be surprised at the number of people who go into nearby buildings to get directions. It's a regular occurrence, an aide told me at the National Grange headquarters down the block at 1616 H St. -- which, if the sign were correct, would be at 1716 H.

This confusion that gripped the city's highway department is rooted in Washington's aberrational geography, which permits diagonal avenues and other odd streets to cut into the middle of the neatly numbered, lettered, alphabetized and numbered streets.

In this case, 16th Street terminates squarely at the north center of Lafayette Park directly opposite the White House, starting the 1600 block. But the western boundary of Lafayette Park is at Jackson Place, the site of this sign, only halfway to 17th Street. But a highway sign erector didn't check his or her map, and assumed differently.