Sky Stage, a new (but temporary) outdoor theater in Frederick, is part art, part hanging garden and part performance hall. (Bill Adkins)

Outdoor theaters offer an intriguing tension between enclosure and openness. Sky Stage embodies the contrast, but that’s just one of several. The structure in downtown Frederick, Md., is rooted yet temporary, high-tech yet handmade and practical yet visionary. It’s both modern sculpture and contemporary architecture, juxtaposed and intermingled.

The building’s story opens in the mid-18th century, when the stone walls that now contain Sky Stage were erected. By some accounts, gun parts used in the American Revolution were manufactured in the building, which later became a warehouse. The current chapter begins in 2010, when the structure was badly damaged by fire. The roof and a brick second story were destroyed, leaving an eyesore and an opportunity.

Enter, a year ago, Heather Clark, a Loudoun County artist who has degrees in real estate development and environmental science and community planning. Clark has constructed pie­ces — like one exhibited at Hillyer Art Space in January — meant only for gallery settings. But she likes to work in everyday environments and to make things with real-world implications.

Plus, Clark has always loved abandoned buildings. “I always want to know what’s inside boarded-up buildings,” she says while conducting a tour of the place.

What’s inside the opened-up structure is at once a work of art, a sort of hanging garden, and space for performance and instruction. Clark and her many helpers built Sky Stage over the summer of 2016, and opened it in the fall. It was dormant for most of the winter, and it ends its run for this purpose July 31, when its owner, General Engineering, reclaims it for eventual redevelopment.

A lighted sign over the otherwise modest entrance announces the venue, while demonstrating a flair for amplifying the functional so that it also becomes decorative. It’s something Clark may have learned from Robert Venturi, Denise Scott Brown and Steven Izenour’s paradigm-shifting 1972 book “Learning From Las Vegas.”

Within the stone facade is wooden-bleacher seating for 140, a conventional array save for a few trees on the upper levels. These “represent life in the space,” Clark notes. The foliage is visible from outside, suggesting that there’s a secret garden behind the rough enclosure.

The wooden edifice, snaking spiral of sedum and steel beams make Sky Stage a “dreamy space,” says Heather Clark, a Loudoun County artist who oversaw the transformation. (Sarah Jo Pixley)

There isn’t, exactly, but the walls do surround another living feature: a wooden spiral and a supporting lattice, topped with a blanket of sedum. The plant requires little water and so is often used for green roofs. (The sedum is watered by precipitation captured in a yellow, 400-gallon rain barrel.) The apparatus, fanciful yet sustainable, might be called a green roof for a building that doesn’t have a roof.

The wooden edifice was designed in collaboration with the Digital Structures Research Group at the Massachusetts Institute of Technology (one of Clark’s alma maters). The serpentine form, which curls through window openings into a separate part of the building and then out again, suggests a roller coaster. Clark prefers a more organic comparison: “I call it the double helix spiral.”

The intricate structure, and the technology that yielded it, sets off the simple stone around it. The irregular stones were quarried with simple tools from a rocky outcropping that’s still visible behind the building; the positioning of the 6,500 wooden pieces was determined by a computer program. Yet both the old building and the new addition were assembled by hand. (The labor, like the space itself, was donated.)

The open-air performance room is surprisingly intimate, and it’s economically arranged. The overhead steel beams that keep the walls in place double as housing for theatrical spotlights. Yet the sculpture makes it, in Clark’s words, “more of a dreamy space.”

The dream is fleeting, which makes practical sense, since the building’s owner will ultimately remake it for a less arty use. Still, it seems odd for this exercise in sustainability to last less than a year.

Clark, however, calls the temporary nature of the endeavor “liberating.” She also says that because of the relatively short time frame, community interest in the project has intensified.

“I think of it,” she says, “as a burst of energy.”

If you go
Sky Stage

59 S. Carroll St., Frederick, Md. 301-662-4190.

Dates: Through July 31.

Prices: Access to the space is free, but it is open only for events and by appointment. Some events charge admission. Upcoming events include a musicians’ open-mic night Friday; salsa dance classes most Wednesdays, beginning Wednesday; and yoga classes Thursday evenings. Starting next month, Sky Stage will host performances by local bands most Saturday nights.