I'll let the sign at the beginning of this path in the Presidio do the talking:
"This trail has witnessed the passing of Spanish solders, Franciscan missionaries and American soldiers of two centuries. It is perhaps the oldest travel corridor in San Francisco. In 1776 this path connected the Spanish Presidio with the mission, three miles to the southeast. During the 1860s it became the main route used by off-duty soldiers to walk into San Francisco. Many of those men made the trip into town to meet their sweethearts, and the trail became know as Lovers' Lane."
The Presidio is a magnificent place packed with history and incredible sights.
It's also a great place to gorge yourself on wild blackberries.