This is Grand Central Terminal’s summer in the sun.

The greatest monument to transportation in New York, its fabled “Gateway to a Continent,” Grand Central has never been as visible from the outside or as luminous from within. Nearby demolition for a major development, One Vanderbilt, can be credited for that.

And soon, for the first time in 26 years, Grand Central will briefly reclaim its role as the Beaux-Arts portal to America’s inland empire. This summer, it will be possible to reach destinations along the Hudson River Valley — Rhinecliff, Hudson and Albany — from under the constellation-flecked ceiling that has had travelers craning their necks for more than a century.

Six of Amtrak’s Empire Service trains will be rerouted every weekday to Grand Central from Pennsylvania Station, Veronique Hakim, the interim executive director of the Metropolitan Transportation Authority, said recently.

On a typical weekday, Amtrak runs about two dozen trains between Penn Station and Albany-Rensselaer under the Empire Service umbrella. Switching six of those trains to Grand Central will relieve some of the pressure on beleaguered Penn Station during urgently needed infrastructure repairs that have already promised to make this a “summer of hell” for travelers.