America’s Largest City Park Hides Ancient Petroglyphs, a Castle, and 50+ Miles of Trails in the Arizona Desert

South Mountain Park, Arizona

This Arizona beauty flips the script on city parks. Instead of manicured lawns, you get 16,000 acres of real Sonoran Desert.

Instead of park benches, you get ancient Native American rock art. And instead of an artificial pond, you get enough hiking trails to keep you busy for months – all while downtown Phoenix glitters in the distance.

Phoenix got this mountain for just $17,000

Phoenix bought South Mountain Park from the federal government in 1924 for only $17,000. This bargain has grown to 16,283 acres today, making it America’s largest city park.

It was first called Phoenix Mountain Park and started with 13,000 acres before growing bigger through programs in the 1970s and early 1980s. Before being renamed, locals knew it as the Salt River Mountains.

This almost became a national park instead

President Calvin Coolidge nearly made South Mountain a national park before deciding to sell it to Phoenix in 1924.

The first park planning team included J.C. Dobbins (chairman of the Phoenix city planning commission), Mrs. John Hampton, and H.B. Wilkinson.

If you drive along Dobbins Road just north of the park, you’re on a street named after the committee chairman who helped create this urban wilderness.

A dad built his daughter a castle from junk

You’ll find Mystery Castle in the foothills, built by Boyce Luther Gulley in the 1930s after he left Seattle with tuberculosis.

This 18-room, three-story castle has 13 fireplaces, a chapel, bar, and even a dungeon. Gulley made it from whatever he could find – old car parts, railroad tracks, telephone poles, and supposedly mixed goat milk into the mortar.

When he died in 1945, his daughter Mary Lou moved in and lived there until 2010.

You can bike on car-free roads every Sunday

On the fourth Sunday each month, the park holds an all-day ‘Silent Sunday’ from 5 a.m. to 7 p.m. when cars can’t use the main road.

On other Sundays, a shorter version happens from 5 a.m. to 10 a.m., with the road closed at the one-mile marker.

You can also access San Juan Road at special times: from 5 a.m. to 7 p.m. on the first Saturday and from 10 a.m. to 7 p.m. on the first Sunday each month.

Workers hauled rocks from across Phoenix to build trails

Back in the 1930s and ’40s, Civilian Conservation Corps camps operated at South Mountain, building the trails, roads, and stone structures you see today.

These workers brought rocks from as far away as North Mountain (near today’s Thunderbird Road) to create park features. Only the strongest workers got the tough job of hauling these heavy stones.

Many of the structures they built still stand, including the stone shelter at Dobbins Lookout.

They planned a mountain tunnel but never built it

Plans once existed for a dramatic 500-foot tunnel straight through South Mountain, connecting Telegraph Pass to a road on the south side.

This big project got official approval but never happened, likely due to money or technical problems. You can still hike Telegraph Pass today to see where this tunnel would have cut through.

The trail climbs 240 feet in elevation and remains one of the park’s most popular paths.

Ancient art covers rocks throughout the park

You’ll spot impressive rock carvings along Mormon Trail, Telegraph Pass, Desert Classic, and Holbert Trails.

The Hohokam people created these drawings as far back as the 1400s. Many park structures include recycled boulders that still show these original markings.

These ancient designs show up best after rain when the wet surface makes the contrast stronger. Keep your eyes open for these historical treasures during your hike.

You can dance on concrete floors under the stars

Picnic areas throughout the park have unexpected concrete dance floors built right into the ramadas. One big group area fits up to 5,000 people and comes with picnic tables, grills, and restrooms.

If you want to reserve these spaces, you need to submit a Special Activity Request Form between 72 hours and 6 months before your event.

You can even get permits for alcohol and music in certain areas if you plan ahead.

More chuckwallas live here than anywhere else in the world

An amazing 60+ chuckwallas per hectare live in each hectare of South Mountain, the highest number ever recorded for these unique lizards. Scientists from Arizona Game and Fish Department confirmed this record-breaking population.

Look for the special orange-tailed males with black bodies that only live in this park. During the South Mountain Freeway construction in 2017-2018, workers safely moved over 100 chuckwallas to protected areas within the preserve.

Rare elephant trees grow right out of the rocks

South Mountain marks the northernmost spot where elephant trees (Bursera microphylla) naturally grow. These weird plants have twisted trunks that look like elephant skin.

You’ll find trees with multiple trunks mostly at higher elevations. Scientists have found these trees need specific combinations of sun exposure, slope, elevation, and warmth to survive this far north, with middle heights working best for them.

A freeway cut through part of the park in 2019

The South Mountain Freeway section of Loop 202, finished in 2019, took away a small piece of the park despite people protesting. Road designers had to change their plans to limit damage to the preserve.

Before construction, Arizona Game and Fish Department moved animals to safer park areas.

Even with this development, South Mountain still covers nearly 17,000 acres with more than 100 miles of trails for you to enjoy.

Eat breakfast on horseback in the desert

At Ponderosa Stables (10215 South Central Avenue), you can take the only official guided horseback rides in South Mountain.

Choose from breakfast rides (starting at 7 a.m.), steak dinner rides (leaving at 5 p.m.), lunch rides, or wagon trips through the preserve.

They keep over 30 horses trained specifically for trail riding. Some trails aren’t suitable for horses, including Telegraph Pass Trail, which has steep sections too dangerous for riders.

Visiting South Mountain Park

South Mountain Park (10919 S. Central Ave, Phoenix) welcomes visitors daily from 5 a.m. to 7 p.m., with trails open until 11 p.m.

The Visitor Center runs Thursday-Sunday from 9 a.m. to 3 p.m. Getting in is free with many trailheads including Pima Canyon, Mormon, and Beverly Canyon. Dobbins Lookout sits at 2,330 feet, giving you panoramic Phoenix views.

Mystery Castle tours happen Thursday-Sunday, 11 a.m. to 4 p.m., October-May. Always bring water, especially during summer when Phoenix regularly tops 100°F.