No through street.

HERE IS THE new pedestrian plaza in front of the White House. The space used to be a typically busy downtown street, but after the 1995 Oklahoma City bombing it was "temporarily" closed to traffic, 9/11 sealed its fate as a city street.

First Lady Laura Bush formally "reopened" this stretch of Pennsylvania Avenue in November, but its permanent transformation into a plaza is really another stage in the closing of what was once the world's most open capital. Many D.C. streets are being narrowed or obliterated, and the city's once-grand open spaces are increasingly interrupted by concrete barriers, chain-link fences, bollards, and armed guards. The Washington Post's editorial page editor, Fred Hiatt, has argued that the experience of Washington now evokes fear, and that "the openness that must be the hallmark of a working democracy" is being lost.

Daniel Patrick Moynihan had the same concerns about the capital in the wake of September 11. Speaking at a symposium on security in November 2001, the former senator noted that "architecture is inescapably a political art, and it reports faithfully for ages to come what the political values of a particular age were." Surely, he added, "ours must be openness and fearlessness in the face of those who hide in the darkness. A precaution, yes, sequester, no."