Sanctuary

"This is the sanctuary. It was built by my great-grandfather to honor the memory of the Assassin Order and protect its secrets."

- Mario Auditore.

The Sanctuary was located in Monteriggioni, and was used by Assassins in both the Renaissance and Modern Times.

It was a well-built, stone chamber found underneath the Villa Auditore, and could be accessed primarily through an entrance hidden behind a bookshelf in the Villa study.

Statues
The Sanctuary was characterized notably by seven statues of seven legendary Assassins, who "guarded the freedom of humanity when it was most threatened."

Six of these statues had corresponding seals at their base, which had to be collected and returned, in order to unlock the gate in front of the seventh statue of Altaïr Ibn-La'Ahad. This seventh statue also held the armor set fashioned by Altaïr.

From left to right, the statues represented:
 * Qulan Gal
 * Darius
 * Wei Yu
 * Altaïr Ibn-La'Ahad
 * Amunet
 * Iltani
 * Leonius

History
The Sanctuary was constructed by Domenico Auditore, and served as a tribute to the greatest Assassins in history.

In 1478, Mario Auditore revealed the Sanctuary to his nephew Ezio as he became devoted to the Assassin's Creed.

Siege of Monteriggioni
During the Fall of Monteriggioni, the Sanctuary was used as a temporary haven for survivors fleeing the attack.

Additionally, a passageway behind the statue of Altaïr served as an escape route for Ezio, his family, and several hundred surviving townspeople. The hidden door led them into the tunnels under Monteriggioni, which were also connected to the Auditore Family Crypt.

Modern Times
"Whoa, they built this place to last. No signs of structural damage, and no cell signal either. This place is perfect."

- Rebecca Crane, upon entering the Sanctuary in 2012.

Centuries later in modern times, a team of Assassins sought out this last Assassin safehouse in Italy, as their first hideout had been found and assaulted by Abstergo.

In September of 2012, Desmond Miles and Lucy Stillman traced back the escape route, in order to unlock the bookcase entrance, and allow Rebecca Crane and Shaun Hastings to gain access to the Sanctuary.

The modern Assassins then used it as refuge, since its underground structure would protect them from Abstergo's cell phone surveillance. However, as the Sanctuary had no electricity, Desmond first free ran around modern Monteriggioni to reroute power into the Sanctuary.

Trivia

 * The circular grate in the courtyard at the back of the Auditore Family Villa is actually the top of the Sanctuary, which allows light in. The sanctuary can't be viewed from the outside.
 * In Assassin's Creed: Brotherhood, though the grate at the top of the Sanctuary appears broken from the inside, when viewed from the outside, it seems undamaged.
 * In Assassin's Creed II, you can examine all the statues except Altaïr's, and gain information about the Assassin. In Brotherhood, only the statue of Altaïr may be interacted with, resulting in a short cutscene that involves Desmond using a stereotypical Italian accent, and Rebecca scolding his racism. This process may be repeated until Sequence 6.
 * The secret exit used during the siege of Monteriggioni is present in Assassin's Creed II, however, it is blocked by a pile of logs. (I couldn't confirm that, behind Altair statue I couldn't see nothing in Assassin's Creed II)
 * Although all of the Assassin statues (other than Altaïr's) have the small skull mechanisms that open the entrances of Assassin's Tombs, they cannot be interacted with.
 * In Brotherhood, these skull mechanisms have been removed from the statues during the siege of Monteriggioni, but reappear in modern Monteriggioni.
 * Desmond can interact with his teammates or certain items in the Sanctuary during each memory sequence and trigger a variety of conversations.