A year ago, if the old Portofino at 206 Thompson Street in Greenwich Village was remembered at all, it would have been as the restaurant where Elaine Kaufman cut her teeth in the early ’60s, before opening her own place uptown.

This year, now the Malt House, it is a landmark in American history — minor, to be sure, but a landmark all the same. The case of United States v. Windsor, which culminated on Wednesday when the Supreme Court struck down the Defense of Marriage Act, can be traced to an evening in 1963 when Edith S. Windsor met Thea Clara Spyer over dinner at Portofino. After half a lifetime together, they were married in 2007.

The rediscovery of Portofino is a reminder that social landmarks don’t make their significance readily apparent. A bit of context is often needed to appreciate the triumphs, disasters and dramas that have played out in these buildings.

The Gay Pride Month 2013 guide (PDF) prepared by Christopher Brazee, Gale Harris and Jay Shockley of the Landmarks Preservation Commission is an engaging reminder that buildings can breathe with life to those who know something about them....