SAN FRANCISCO — On bike and on foot, people hit the hilly paths of the Presidio, the national park on a former Army base in San Francisco, many of them heading toward the northwest corner of the park overlooking the Golden Gate Bridge.

Tour buses pull up at a visitors’ plaza here, disgorging passengers who gawk at the view while buying souvenirs and snacks.

But just inland, it’s a decidedly quieter scene. The only sound is the song of sparrows as wind ripples long grasses on what was once a parade ground. Here at Fort Winfield Scott, clay-roof Mission Revival buildings dating to the early 20th century — once barracks for soldiers who operated artillery defense of the Pacific coastline — stand largely empty.