Secret Places, Hidden Sanctuaries: Uncovering Mysterious Sites, Symbols, and Societies is a 2009 book called a "robust and skeptical look at the kind of esoteric nonsense celebrated in The Da Vinci Code

The Da Vinci Code

The Da Vinci Code is a 2003 mystery-detective novel written by Dan Brown. It follows symbologist Robert Langdon and Sophie Neveu as they investigate a murder in Paris's Louvre Museum and discover a battle between the Priory of Sion and Opus Dei over the possibility of Jesus having been married to...

."

The book itself covers various sites and societies favored by conspiracy theorists and unexplained mystery enthusiasts, including Rosslyn Chapel

Rosslyn Chapel

Rosslyn Chapel, properly named the Collegiate Chapel of St Matthew, was founded on a small hill above Roslin Glen as a Roman Catholic collegiate church in the mid-15th century...

, Area 51

Area 51

Area 51 is a military base, and a remote detachment of Edwards Air Force Base. It is located in the southern portion of Nevada in the western United States, 83 miles north-northwest of downtown Las Vegas. Situated at its center, on the southern shore of Groom Lake, is a large military airfield...

, Skull and Bones

Skull and Bones

Skull and Bones is an undergraduate senior or secret society at Yale University, New Haven, Connecticut. It is a traditional peer society to Scroll and Key and Wolf's Head, as the three senior class 'landed societies' at Yale....

, Opus Dei

Opus Dei

Opus Dei, formally known as The Prelature of the Holy Cross and Opus Dei , is an organization of the Catholic Church that teaches that everyone is called to holiness and that ordinary life is a path to sanctity. The majority of its membership are lay people, with secular priests under the...

, the Esalen Institute

Esalen Institute

Esalen Institute is a residential community and retreat in Big Sur, California, which focuses upon humanistic alternative education. Esalen is a nonprofit organization devoted to activites such as meditation, massage, Gestalt, yoga, psychology, ecology, and spirituality...

, Mount Weather

Mount Weather

The Mount Weather Emergency Operations Center is a civilian command facility in Virginia, U.S. used as the center of operations for the Federal Emergency Management Agency...

, Heinrich Himmler

Heinrich Himmler

Heinrich Luitpold Himmler was Reichsführer of the SS, a military commander, and a leading member of the Nazi Party. As Chief of the German Police and the Minister of the Interior from 1943, Himmler oversaw all internal and external police and security forces, including the Gestapo...

's Wewelsburg

Wewelsburg

For the village of Wewelsburg see Village of WewelsburgWewelsburg is a Renaissance castle located in the northeast of North Rhine-Westphalia, Germany, in the village of Wewelsburg which is a quarter of the city Büren, Westphalia, in district of Paderborn in the Alme Valley. The castle has the...

 Castle, Montecristo

Montecristo

Montecristo is a small Italian islet, approximately 4.3 kilometers across at its widest point, located about halfway between Corsica and mainland Italy; south of Elba and west of Giglio. It is part of the Tuscan Archipelago...

 island and Disneyland's Club 33

Club 33

Club 33 is a private club located in the heart of the New Orleans Square section of Disneyland. Officially maintained as a secret feature of the theme park, the entrance of the club is located next to the Blue Bayou Restaurant at "33 Royal Street" with the entrance recognizable by an ornate address...

.

In this work, the authors seek to put forward new evidence (and novel theories) about some 150 controversial places and legends, including the following hypotheses:

• That the Mediterranean island of Montecristo
  Montecristo
  Montecristo is a small Italian islet, approximately 4.3 kilometers across at its widest point, located about halfway between Corsica and mainland Italy; south of Elba and west of Giglio. It is part of the Tuscan Archipelago...
  
  , an Italian government exclusion zone forbidden to visitors without special permission, may conceal the greatest hidden treasure of all time—the immense booty of Turkish pirate and admiral Turgut Reis
  Turgut Reis
  Turgut Reis was an Ottoman Admiral and privateer who also served as Bey of Algiers; Beylerbey of the Mediterranean; and first Bey, later Pasha, of Tripoli. Under his naval command the Ottoman Empire maritime was extended across North Africa...
  
  .

• That contrary to the commonly-held view that Yale's Skull and Bones
  Skull and Bones
  Skull and Bones is an undergraduate senior or secret society at Yale University, New Haven, Connecticut. It is a traditional peer society to Scroll and Key and Wolf's Head, as the three senior class 'landed societies' at Yale....
  
   society was founded as a chapter or branch of a German university "corps
  German Student Corps
  Corps are the oldest still-existing kind of Studentenverbindung, Germany's traditional university corporations; their roots date back to the 15th century. The oldest corps still existing today was founded in 1789...
  
  ," it bears none of the hallmarks of a student corps, but rather resembles the esoteric and Masonic lodges of early 19th century Germany.