Hundreds of feet beneath the sun-drenched beaches and historic avenues of a picturesque California city lies a 200-year-old network of hidden subterranean tunnels.

A new video reveals narrow concrete passages under Ventura, lined with decades of colorful graffiti and long stretches of darkness leading into unexplored depths beneath the coastal town.

Locals continue to wonder about the city’s past buried in the dark, leading to multiple conspiracy theories.

The subterranean infrastructure beneath Ventura County is said to have evolved across distinct historical eras –– dating back to the late 18th century when Indigenous Chumash laborers and Spanish missionaries had constructed the San Buenaventura Mission Aqueduct.

According to the California Office of Historic Preservation, this seven-mile masonry water system featured elevated stone viaducts, subterranean holding tanks and filtration channels that piped water directly from the Ventura River to the mission settlement.

Decades later, during the late 1800s California petroleum boom, early oil companies bypassed traditional surface drilling by hand-carving horizontal oil tunnels over 1,500 feet deep into the rock faces of Sulphur Mountain and Adams Canyon.

The new video was shared by local underground radio station The Red Light District Show, which is based out of the city.

Just like Ventura, a California town known for Danish pastries, Solvang, also has a network of underground tunnels that have sparked years of speculation — but no clear historical explanation for why they were built.

The tunnels have inspired plenty of colorful theories, including claims they once connected to brothels hidden beneath the charming village.

Wes Leslie, whose walking tour company explores Solvang’s hidden history, said he has spent years digging into the mystery and recently began sharing his own underground investigations online.

“It’s hard to tell if there’s any merit to some of these stories, or if it’s just fun tall tales and urban legends,” Wes Leslie, owner of Secret Solvang, told SF Gate.