You have to buy Assassin's Creed 2: Black Edition.
It is located In Monteriggioni. Just go near the Villa and you will see the crypt.
The assassins crypt at the Monteriggioni Villa contains 6 statues of famous assassins. When you collect all 6 seals from the various assassin's tombs, it will grant you access to Altair's armour - the protagonist from the first game.
it is under the family mansion. over the game you can complete various tombs hidden away which allow you to get seals. once you have all 6 (which i do) you go back to the crpt and place the seals on the statues. this unlocks altairs armor.
Triangle, square, left, L1, left, circle
There were two black robe sets in ACII - Ezio's standard robes could be dyed wetland ebony, and the Armour of Altair were black by default. -You could dye Ezio's robes Wetland Ebony at one of the tailors in Forli -Altair's robes could only be unlocked after all 6 assassin seals were acquired and placed in the crypt beneath the Villa Auditore
crypt crypt
Crypt - On
To get to the chaos crypt you will have to go to SHADOWFALL and talk to GRAVELYN and do the CHAOS CRYPT quest.
Probably the expression looked for is crypt.
Crypt of the Wizard was created in 1996.
Crypt Chambers was created in 1858.
Crypt Killer was created in 1995.