The Sooner State is full of history and with that comes secrets that have unraveled over time. From hidden places to little-known facts, and even secret tunnels in Oklahoma, here are 11 amazing Oklahoma hidden gems and secrets you never knew existed:

1. A Chinese underground society once existed in tunnels under Oklahoma City.

Hidden passages below the city were filled with a rarely-seen Chinese community. Anti-Chinese sentiments drove the culture underground across the country, including Oklahoma City. During a flu epidemic during the 1920s, health inspectors stumbled across the Chinese underground. After their inspection, the inspectors were quoted as saying the nearly 200 residents were "in good health and surroundings and sanitary as all get out." An entire network of tunnels downtown that link various buildings to each other still exists today.

2. This location in Oklahoma is hidden on Google Earth.

It is U.S. Air Force AWAC's parked at coordinates 35 25 27.60N 97 23 30.63W. Although it isn't very secret if it's on the big "G" is it?

3. The Heavener Runestone may prove that Vikings were the first Europeans to set foot in present Oklahoma.

Although still controversial, it is very probable that the Vikings erected the 12 ft. tall stone pillar at the Heavener Runestone. Its inscription dates back to AD 600-900, making it one of the oldest "old rocks" in America.

4. Oklahoma State University's Stillwater campus has a vast network of steam tunnels that are part of the university’s utility distribution system.

Some of the tunnels date back to before the 1940s. In 1936, an explosion from a leaking natural gas line in one of the tunnels rocked OSU’s campus.

5. Oklahoma City’s City Place skyscraper has a spiral slide in a central shaft of the building that spans all 33 floors.

The slide was part of the building’s original fire escape system and is still usable.

6. A secret cave exists in Stephens County that was once the hideout of the legendary outlaw Marlow brothers.

Legend has it, the Marlow brothers use to avoid capture from law enforcement by hiding in a cave on Wild Horse Creek. In June 2004 a city worker discovered the cave after the tire of his riding mower fell through a sinkhole.

7. The boathouse at Ponca City’s grandiose Marland Mansion, is connected to the main building by an underground tunnel.

The Marland Mansion tunnel also connects the mansion to an art studio on the grounds.

8. An underground tunnel system runs below downtown Tulsa.

A system of secret underground tunnels was built in the late 1920s to connect many of Tulsa’s early skyscrapers. In all, the Tulsa tunnels connect eight buildings, three parking garages, an upscale hotel, and numerous cafés and small businesses. It’s possible to go from Fifth and Boston to First and Main while staying indoors the entire time. Shown above is The Vault located at 320 S. Boston - beneath the streets of downtown.

9. A few floors up from street level on Automobile Alley is a collection of classic cars that would raise any car enthusiast's eyebrows.

Have you ever seen them? It sure would be a nice place to pick up a ride to this 1950s diner in Oklahoma.

10. Many Starbucks locations in the Sooner State have a secret menu.

Starbucks allows customers to make their creations available as long as the location has the ingredients on hand and the barista knows the recipe. Try these suggestions: Butterbeer Latte or Frappuccino; Three C’s Latte; Fruity Pebbles Frappuccino; Chocolate Dalmatian; and Raspberry Caramel Macchiato.

11. A Roller Coaster Road exists in Seminole County.

If you haven't discovered this road in Oklahoma yet - go now! The technical name of this road is "County Road NS 366." It's one mile west of "Old Highway 56, and about 1.5 miles west of State Highway 56, just north of Wewoka, Oklahoma. If you're prone to car sickness, bring a brown paper bag.

Fast forward to 2:45 to see this Oklahoma location that is hidden on Google Earth:

It turns out there are a lot of hidden mysteries and secrets in OKC we didn't know about. Were you surprised to find out about any of the secret tunnels in Oklahoma, or the delightfully delicious hidden menu items at Starbucks? Tell us about your favorite Oklahoma secrets with a comment - just don't say it out loud, they are secrets after all.

Please note: Some images were not available and a similar photo was substituted in its place. (Like the Starbucks drinks, everyone must have slurped them down so fast they forgot to take a photo)