Unlocking the Secrets in Indiana Jones and the Great Circle

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Indiana Jones and the Great Circle is a game that encourages you to explore. The first major open-world area you’ll encounter is Vatican City, where you’re able to enter the Sistine Chapel using a key provided by Antonio. While the main objective here is to meet Sister Catherine and initiate her quest, there’s an intriguing puzzle waiting for those who investigate further.

At the rear of the Sistine Chapel, you’ll find a locked safe. With a bit of detective work, you’ll be able to uncover the combination and open it.

How to Begin the Secret of Secrets Mystery

You can access the Sistine Chapel in the southern section of Vatican City, provided you have the priest disguise along with the Clerical Key from Antonio. Navigate through the Borgia Gardens and use your key to unlock the main entrance.

It’s a good idea to grab your camera before heading to the Sistine Chapel, as there are numerous photo ops that will earn you extra Adventure Points.

Once inside, talk to Sister Catherine, ideally snapping her picture if you haven’t done so already. Next, head to the back of the chapel and open the door on your left. There, read the note on the table to kick off the Secret of Secrets Mystery.

Make sure to capture an image of the chapel’s renowned ceiling while you’re there. The best spot for this photo is on the steps next to the seated priest on the left side of the room.

How to Unlock the Safe in the Sistine Chapel

The note from Nicoletti references an original manuscript from the 12th century that’s kept inside the safe across the room. It provides a clue for the combination:

“Look to the stars and the saints: Peter with the key, then Paul with the sword.”

Next to the table with the note and facing the safe, you’ll notice three small statuettes in the room:

A marble statue of Saint Anthony on the left.
A wooden statue of Saint Paul directly in front of you, near the safe.
A wooden statue of Saint Peter on the right, situated close to the locked door that leads back to the main chapel area.

Following the note’s guidance, only the statues of Peter and Paul matter for this puzzle—you can disregard Saint Anthony. Take the Peter and Paul statues and turn them over to check the symbols on their bases. They each have two planetary symbols painted on them.

Due to how Indy holds the statues, the symbols may appear upside-down. According to the order needed (putting Peter first, followed by Paul as per Nicoletti’s letter), the sequence is Mars, Mars, Uranus, Mercury.

You can open the safe simply by knowing the planetary order. Mars is the fourth planet from the sun, Uranus is the seventh, and Mercury is the first, making the safe’s combination 4471. If you need additional guidance, a Planetary Chart is available in a drawer at the center table.

All Mystery Note Locations for Secret of Secrets

Note	Location
Nicoletti’s Letter	Found on the table on the right as you enter the room at the back of the Sistine Chapel.
Planetary Chart	Inside the drawer in the middle of the puzzle room.
Hidden Note	Under the book in the safe.

Though the manuscript within the safe is a forgery, retrieving it will reveal the final Mystery Note related to the Secret of Secrets, hinting at an impending visit from a German dignitary amid Mussolini’s forces securing the Vatican. You will also receive the Adventure Book for the Cutman Skill, which enhances Indy’s health recovery rate.

After solving the mystery, proceed to the back of the room and take the stairs down. Use the Clerical Key to unlock the door at the bottom, then present the priests with the photo of the Sistine Chapel ceiling. Lastly, unlock the exit door to create a convenient escape route for future use!