A map of Boomeria, the medieval-style, science-focused adventure land. (Photo courtesy of Preston Boomer)

How to describe the Kingdom of Boomeria, the hillside residence of retired high-school science teacher Preston “The Boom” Boomer, tucked in the mountains of Santa Cruz, California? Four words: “Not your typical home.”

That is according to its owner, Boomer. It’s an accurate summation: most homes are not equipped with watchtowers, water cannons, a dungeon, a guillotine, and 400 feet of dark and musty catacombs.

The Kingdom of Boomeria became a playground for curious science students in 1956, when Boomer began teaching physics and chemistry at San Lorenzo Valley High School. The Boom’s eccentric antics in the classroom—he was famed for his exploding experiments, often performed while wearing a wizard cape—soon spilled over into his home. He began inviting students to his residence among the redwoods, which at the time was equipped with a newly salvaged 19th-century pipe organ Boomer used for both musical entertainment and informal lessons in harmonics.

The students took him up on the offer, and, in doing so, helped forge the legend of Boomeria. The pipe organ was just the beginning: over several years during the 1960s, The Boom and his students worked together to build a castle, rig up water cannons, and dig winding tunnels beneath the castle dungeon, accessed via trap door. All of this medieval-style mayhem was—and still is—ruled from the CIC, or Combat Information Center, where The Boom can issue orders via speakers and microphones hidden around the property.

The Boom at Boomeria’s castle. (Photo courtesy of Preston Boomer)

After 56 years of ruling the classroom labs at San Lorenzo, The Boom retired in 2013 at the age of 81. He did so reluctantly: ankle and knee surgery forced him to renege on a promise to teach until he dropped dead on the lab table. Boomer  retirement, however, has not slowed down the operations of Boomeria. Anyone is welcome to explore the grounds as long as they call or email ahead. (As for how people find out about Boomeria now that he is retired, Boomer says they are informed of its existence by “friends, relatives, and parolees.”) 

Now 83, Boomer continues to host events at Boomeria, including water-cannon battles, music camps, summer organ concerts, and even a Halloween Steampunk-themed wedding in 2013. While the place has gathered a little rust and mold since 1956, the grounds are still mind-boggling for first-time visitors, who encounter sentry towers, “attack ducks,” and a Main Aqueous Ammunition Bunker (a feature the less imaginative might call a “swimming pool”).

What is Obscura Day? It’s more than 150 events in 39 states and 25 countries, all on a single day, and all designed to celebrate the world’s most curious and awe-inspiring places. To get ticket information for the Boomeria tour on Obscura Day, go here. 

The Boom in the classroom with a fire extinguisher at the ready. (Photo courtesy of Preston Boomer)