SAN DIEGO — What did America’s Finest City’s downtown skyline and waterfront look like a century ago?

Basically unrecognizable, according to photos shared by the San Diego History Center, which is on a mission to preserve the city’s unique past.

According to the organization’s historians, San Diego’s population was just under 75,000 at the start of the 1920s, and a decade of growth followed.

The photos, ranging from 1921 to 1929, provide a fun snapshot of the developing coastal city. Some recognizable landmarks are already in place — you can make out the iconic Cabrillo Bridge and California Tower in the distance of a shot from the start of the decade. They were still new attractions then, built in time for the Panama-California Exposition in 1915. Today, they remain instantly recognizable hallmarks of Balboa Park.

Over the course of the 20s, more enduring local attractions opened, from Lindbergh Field to the El Cortez Hotel and the Fox Theatre. A little further north, the Mission Beach Amusement Center (now Belmont Park) opened with its Giant Dipper rollercoaster in 1925.

But today’s recognizable skyscrapers, the steel-mesh dome of the San Diego Central Library, the stunning venue that is Petco Park — all those developments were still dreams of the distant future.

If you’re curious about how more of the city filled in over time, the History Center is an excellent resource. The photos shared for this article represent a small slice of the city’s past that has been lovingly documented by the organization, which you can visit in Balboa Park.

Located in the heart of the park near the Fleet Science Center, the museum has rotating exhibitions open to the public. It is one of the oldest and largest historical organizations on the West Coast.

The museum opens to the public each weekend — Friday through Sunday from 10 a.m. to 4 p.m. Admission is donation-based. The organization does not charge a fixed admission fee, but suggests a minimum donation of $5. It encourages those who can offer more to do so, helping keep the center up and running.

Learn about the San Diego History Center’s hours, admission policies and more on their website.

And if you love historical photos, you can also purchase high-quality prints from the museum for your home or office.