where is the manticore diagrams in prison in witcher 3?

The Manticore diagrams in The Witcher 3: Blood and Wine are found at the ruins of Bastoy Prison for the first piece, specifically the Manticore Steel Sword diagram. It’s in the tower area inside the prison ruins, behind a loose brick or hidden compartment.

Where to look

• Go to Bastoy Prison ruins in Toussaint.

• Head to the large tower at the northeast end of the ruins.

• Climb up and use Witcher Senses to find the hidden brick/compartment.

• The first diagram and a note are inside, which points you to the next location.

If you meant the whole set

The rest of the Manticore diagrams are spread across Toussaint, including:

• Armor in a cave near Termes Palace Ruins.

• Boots and trousers in Lebioda’s Temple.

• Gauntlets in a lake near Dun Tynne Crossroads.

• Silver Sword in a later cave location tied to the scavenger hunt.

The prison location people usually mean is Bastoy Prison ruins , where the hunt starts.

TL;DR

Go to Bastoy Prison ruins in Toussaint , climb the tower, and search the hidden compartment with Witcher Senses to get the first Manticore diagram.