Tunnel

"We recently began traveling through the tunnels to avoid the guards, but many of the entrances in the city are broken. By using them, we can get to our destination rapidly, without encountering resistance."

―Niccolò Machiavelli about the tunnels.

An entrance to the tunnels.

Tunnels were a means of travel in Rome and Constantinople, and were the equivalent to the Fast Travel Booths. Ezio was first introduced to the tunnels by Niccolò Machiavelli, wherein he stated that the tunnels were used to arrive at destinations rapidly, while avoiding guards. There were a total of nineteen tunnel entrances throughout Rome.

Renovations

Initially, there was only one available tunnel entrance, leaving the other eighteen to be renovated by architects. The three tunnels that were located outside of the Rosa in Fiore, Barracks, and the La Volpe Addormentata would be automatically renovated once the respective building fronting it was; making them the only ones that were required to be restored.

Each district could be accessed via tunnel with the exception of the Vaticano District. Every standard entrance to the tunnels look alike, and had the letters SPQR (Senatus Populusque Romanus) engraved over their gates.

It should be noted that tunnels are already available and do not need to be renovated in Assassin's Creed: Revelations.

Tunnel Locations (in Rome)

Ezio and Machiavelli near a tunnel.

Centro District

• Tiber Island Hideout
• Piazza del Popolo
• Augustus Mausoleum
• Pantheon
• Campidoglio
• Rosa in Fiore
• Porte Tevere

Campagna District

• Barracks
• Northern Campagna
• Southern Campagna
• Castra Praetoria
• Terme di Diocleziano
• Colle Viminale

Antico District

• Colosseum
• Porta Nomentana
• Palazzo Laterano
• Terme di Caracalla
• Thieves Guild
• Roman Forum

Tunnel Locations (in Constantinople)

• Fatih Camii
• Arcadius
• Galata
• Hideout
• Galata Mosque
• Bayezid Camii
• Gul Camii
• Arsenal
• Hagia Sophia
• Hippodrome
• The Grand Bazaar
• South Port
• Sofia's shop

Trivia

• In the novelization of Brotherhood, Machiavelli says that Giovanni Auditore discovered the tunnels.
• In Brotherhood, Ezio makes use of the tunnels, there is a brief cutscene of him opening the latch on the gate and entering, though the player is not able to see or travel through the tunnels themselves. In Revelations, the cutscene was omitted, with the screen only fading to black whenever accessing the tunnels.
• Ezio can make use of a special tunnel to pass directly from the Tiber River into the Tiber Island headquarters.
• Tunnel entrances will glow white while using Eagle Vision.
• When you go in a tunnel during a mission or assassination contract, all progress in it will be lost.
• In Revelations, it is unknown how the Galata district tunnels connect with the other districts' tunnels even though there is a large body of water across them.

Source

• Assassin's Creed: Brotherhood