Located in the coveted Ashbury Heights neighborhood, 1550 Masonic Avenue is a one thousand one hundred seventy-five-square-foot, 1940's detached residence featuring two bedrooms and one bathroom on the main level, with additional multi-purpose space below. This tunnel-entrance home sits on an oversized three thousand one hundred twenty-five-square-foot lot, offering significantly more depth than the standard San Francisco parcel. The main floor is centered around an open-concept living, dining, and kitchen area. This bright space is anchored by a central island and flows toward two well-proportioned bedrooms and a remodeled bathroom. Large windows and a rear deck overlook a lushly landscaped yard featuring mature plantings and stone walking paths. The lower level provides a versatile suite with a full bathroom. Currently used as a guest suite or home office, this space offers direct access to the garden and garage. Given the exceptional lot depth and existing height guidelines, the property potentially represents a significant opportunity for expansion either by extending the footprint toward the rear or adding a vertical level to match the scale of neighboring grand-scale estates. Situated just above Cole Valley, the home is two blocks from Buena Vista Park and within easy reach of the Randall Museum, Golden Gate Park, and the shopping districts of the Castro and Haight-Ashbury.