SAN DIEGO » If you’d visited San Diego’s Balboa Park in the past 79 years to climb the handsome California Tower and look for reminders of 1915 — well, never mind. You couldn’t.

Although the tower is the park’s most widely visible structure — and its most obvious artifact from the 1915 Panama-California Exposition — its interior was closed to the public in the 1930s for reasons that are no longer clear. But now, as San Diego celebrates the expo’s centennial, the 200-foot-high tower is open again (to paying customers).

And even if you don’t sign up for the climb, you’ll see reminders of 1915 throughout the park’s core area.

SOME HIGHLIGHTS:

The California Building (which includes the tower) was the centerpiece of the 1915 expo, and its exterior has become emblematic of the city. Its interior is home to the Museum of Man (special exhibitions in 2015: monsters, beer and instruments of torture). The building features a colorful tiled dome, an elaborately ornamented facade and St. Francis Chapel, a nondenominational chapel that’s mostly used for weddings. As for the tower, daily 40-minute tours (weather permitting) started Jan. 1. Museum admission is $12.50 for adults, plus $10 for the tower tour. Info: www.californiatower.org.

The Botanical Building is a domed indoor-outdoor temple of redwood lath, fronted and reflected by a stately lily pond. The gardens inside feature cycads, ferns, orchids, palms and scores of other plants. It’s free but it’s closed Thursdays and holidays. (Among its neighbors: the San Diego Museum of Art, which looks like an expo building but isn’t; and the Timken Museum, which looks like a Modernist interloper from 1965 and is.)

The buildings now known as the Casa de Balboa, the Casa del Prado and the House of Charm went up along the Prado promenade in 1915 as temporary structures, mostly of wood and plaster. They were supposed to be leveled soon after the fair closed, but people kept finding reasons to keep them (including another expo in 1935).

Since 1967 a group called the Committee of One Hundred has raised funds and support for their reconstruction. Now, with the House of Hospitality, they house dozens of cultural enterprises, including the Museum of Photographic Arts; a model railroad museum; youth performing arts organizations; the Mingei International Museum, which focuses on folk art; a visitor center; and the park’s premier restaurant, the Prado, whose cuisine might be described as "global eclectic."

The San Diego History Center (in the Casa de Balboa) has organized two exhibitions: "San Diego Invites the World: The 1915 Expo," to run from Saturday to March 31, 2016; and "Masterworks: Art of the Exposition Era," running through Jan. 3. The center is also screening a 30-minute documentary, "Balboa Park: The Jewel of San Diego," usually at 11 a.m. and 1 and 3 p.m. daily. Call 619-232-6203 to be sure.

The Spreckels Organ Pavilion includes the Spreckels Organ, one of the world’s largest outdoor organs, with 4,530 pipes. At 2 p.m. every Sunday, there’s a free hourlong organ concert. Just about any time, the pavilion’s seats give you a chance to sit and relax.

The San Diego Zoo, now a 100-acre landmark (zoo.sandiegozoo.org) with a sibling San Diego Zoo Safari Park near the northern end of San Diego County, was conceived during the second year of that first expo. Its first animals, including a bear named Caesar, descended from a group that was displayed along the San Diego expo’s Isthmus midway in 1916.

Cabrillo Bridge, designed as the expo’s grand entrance, is a concrete span of seven arches over Cabrillo Canyon and California Route 163. It was closed to cars for seismic upgrades and other repairs in early 2014 but is now open to pedestrians, cyclists and cars approaching from the west on Laurel Street.

Christopher Reynolds, Los Angeles Times