Currently partially restored but short on funding, the Abyssinian Meeting House is the only recognized Maine stop on the Underground Railroad.

"The world's first domed indoor, air conditioned stadium," Houston's Astrodome is currently plagued by code violations that prevent events from being held inside. The last concert was held more than a decade ago.

Built in the 1880s by Chinese laborers who immigrated to work on the transcontinental railroad, this former general store is the last historic structure in the area remaining from that era. The Cucamonga Valley Water District, the building's owner, is planning to demolish the structure, but injunctions have so far prolonged its life.

Montana, once home to dozens of one-room schoolhouses, is seeing their numbers decline as rural populations dwindle. This historic schoolhouse in Polaris, Montana currently serves just four students.

The natural beauty of the James River is matched only by its historic significance. The first permanent English settlement in the Americas, Jamestown, lies along its banks, but the immediate area is threatened by plans to construct an electric transmission line across the river.

Built in stages from 1912 to 1940, the Kake Cannery was one of the first salmon canneries in Alaska. Today the aging structures are deteriorating, despite a 1997 designation as a National Historic Landmark.

Built in 1532, the San José Church in San Juan, Puerto Rico has been closed for 13 years. A restoration was commenced in 2002, but has recently stalled, leaving the future of this early Spanish landmark in jeopardy.

A frequently emulated early foray into comprehensive city planning, the Village of Mariemont is currently threatened, according to the National Trust, by a proposal known as the Eastern Corridor Project. That project would place a highway straight through the village and its 80-acre park.

A 1960s icon, synonymous with the early "jet set," the Worldport at JFK Airport saw its last flight depart in May. Now the famous terminal is slated for demolition, unless preservationists succeed in having it designated a historic place.