WASHINGTON — The depressed highway is a road from nowhere, the remnant of an Interstate once planned to cut through residential neighborhoods. Activists blocked the larger plan for the freeway in the 1960s, so this small segment close to the Capitol is left to feed traffic from city streets to other freeways, leading south over the Potomac to Virginia and east across the Anacostia River.

The scuttled plan left an open gash — a six-lane trench — that divided Capitol Hill from downtown Washington’s East End. Now, a large air rights project is underway to cover the trench with five buildings, bringing with them 2.2 million square feet of offices, apartments, public spaces, shops and restaurants.

Covering three square blocks, it will bridge a divide in the city and restore Pierre L’Enfant’s original street plan for the nation’s capital.

The seven-acre project, called Capitol Crossing, also entails moving an 1876 synagogue, Washington’s oldest and more recently a museum of local Jewish history.