The first Inscription is found in the garden of the Via di Belvedere map area. It is found on the corner near the scaffold arrangement, an area you might've seen if you searched carefully for the missing cat for A Free Spirit Mystery. Take a photo using the camera to earn the first Inscription.
Second Inscription
The second Inscription is easy to find; it's located in the fountain in the Belvedere Courtyard. You shouldn't have any problem running across the Courtyard and snapping a quick photo of the Inscription on the fountain, so long as you keep your distance from the patrolling Blackshirts.
Third Inscription
The third Inscription involves some climbing and parkour just above the Belvedere Courtyard. Climb the scaffolding structure behind the stage in the Belvedere Courtyard. Use your whip to climb to the top and reach the balcony of the Belvedere Courtyard. Cross the black-and-white checkered floor to find the third Strange Inscription on the wall, and take a picture with your camera.
Fourth Inscription
Locate your fourth Inscription, which isn't that hard, actually if you start off by starting from the location you find the third Inscription in. Begin by entering at the Belvedere Courtyard Balcony then go up and enter via the window into the Apostolic Palace.
Look out the other window and use Indy's whip to grapple up to the roof overlooking the Borgia Courtyards. Take a picture of the fourth Insignia, which consists of three graves, shown in the map above.
Fifth Insignia
The fifth Inscription is conveniently located just to the left of the Fountain of Confessions puzzle. You’ll find it at the top of the stairs in the southwest area of the map, specifically within the Vatican Gardens. Capture an image of the Inscription, showcasing two figures.
Sixth Inscription
Find the sixth Inscription at the Blackshirt camp, which is the south part of the map and where you can also gain the Blackshirt disguise. This area is tricky to find as it requires walking through the main storyline of The Stolen Cat Mummy, specifically when you first meet with Gina.
Once you have spoken with Gina, use the zip line behind her to swing over to the opposite balcony, and through the hole in the wire fence. Use Indy's whip to swing down into the camp below you for a fight with three Blackshirt enemies to earn yourself a Blackshirt uniform and a key. Once the fight concludes, feel free to capture a photo of the sixth Inscription located in the corner by the door, as shown above.
Seventh Inscription
The seventh Inscription can be found in the Museum section of the map, accessible during Gina's 'A Nun in Trouble' side quest. Upon your arrival at the Museum, head to the top of the steps in the external gardens to discover the seventh Inscription, as illustrated on the map above. Capture a photo to commemorate the seventh Inscription in your Journal.
Inscription Eight
The eighth Inscription is located in the far right corner of the Excavation Site. It is not exactly easy to find from the Inscription map markers; it seems it is beneath the Site or buried in the rubble. You won't have to search far for the tenth Inscription—it's conveniently located at the top of the Excavation Site, tucked away in a corner, as shown in the image above. Take a photo to complete the eighth Inscription.
Ninth Inscription
To get to the ninth Inscription, you will need to get the Sewer Key that will give you access to the Sewers beneath the Tower of Nicholas V. Get the Sewer Key by conversing with Sister Catherine and Antonio during the 'Mad Priest' Fieldwork quest. Use the key to unlock the locked gate in the Tower of Nicholas V.
Follow the white paint markers on the pipes nearby and use your whip to climb up and make your way through the Sewers. As you reach the end of the Sewer track, head toward the wall with the ninth Inscription, above, before you proceed into the Apostolic Palace.
Tenth Inscription
The final one, the tenth Inscription, can be found in the Cellar-just down the steps beside the Vatican City Post Office. To access the Cellar, you will have to get your hands on the Cellar Key first. The Cellar Key can only be obtained while doing the 'A Savage Discovery' Fieldwork quest: your mission will be to look for a missing Stone Tablet.
In 'A Savage Discovery,' you will come across a point in your quest where you are to locate and engage a worker named Giuseppe. Once you have defeated Giuseppe, make sure to scavenge his body for the Cellar Key. You can use this key to enter the Cellar, where you will find the tenth Inscription hiding in the corner of the room as you progress through the 'Savage Discovery' quest.
Follow the way to reveal how to unlock the Path of Junia Achievement in Indiana Jones and the Great Circle.
Once you have taken pictures of all 10 Inscriptions, return to Antonio, who is waiting for you in the Apostolic Library. You'll need to hang all the pictures on the notice board nearby to complete The Secret of the Giants Fieldwork. Finally, collect your Ancient Relic on the table as a reward.
Not long after, you’ll receive a notification confirming that you’ve unlocked the Path of Junia achievement, granted for successfully returning all 10 Inscriptions to Antonio.
This is everything you need to know about How To Complete Secret Of The Giants in Indiana Jones And The Great Circle, here you have all the ideal steps to achieve it.