The tunnel to the subterranean bunker that played a pivotal role in the liberation of Paris is long and narrow, each step down deceptively steep.

It takes 100 of those steps to reach the former military command post where, for six days, members of the French Resistance helped orchestrate the city’s release from the Nazi occupation in 1944.

For decades after the liberation, the bunker, in the southern end of the city, languished in neglect, abandoned and visited only by urban sewer explorers or tagged and occupied by squatters.

But on Aug. 25, when the French capital marks the 75th anniversary of its liberation during World War II, the newly restored underground shelter will be inaugurated as part of the redesigned and relocated Musée de la Libération de Paris-Musée du Général Leclerc-Musée Jean Moulin — an unusually long name aimed at honoring key heroes of the French Resistance.