While the first game's soundtrack is not as memorable as, for example, the second, the theme of Jerusalem, appropriately named City of Jerusalem, is most definitely extremely beautiful. What makes it even better is the fact that composer Jesper Kyd combined Middle Eastern with Christian music themes to show how the city was still separated into Muslim and Jewish parts back then.
"Access the Animus". Nine minutes of exactly why Assassin's Creed I wins so very, very hard. A steady progression from quiet and deadly atmospheric ambience to stealthy evasion to outright incredible action music.
"Red in the Face". Just the action music part. It's almost worth getting detected just to listen to this while freerunning.
Although only an advert, the music to the Assassin's Creed: Revelationstrailer was just brilliant.
"City Of Rome" from Brotherhood, while similar to "Flight Over Venice", has a haunting depth to it.
The most distinctive score is Ezio's Family which is played in opening sequence of the game. It may give you second thoughts after you discover the Auditore family's fate.
Heart, is great as well especially as it plays when Ezio finds his father's iconic Assassin's robes and suits up for the first time.
Venice Rooftops, which plays during most race and courier sequences, both in the main story and in side missions. Later remixed for Ezio's crossover in Soul Calibur V.
Careful listeners will notice the remixes of "Ezio's Family" that run through this peace. It is particularly poignant that said remixes can be taken as a reference to Ezio's own thoughts as he free-runs, remembering back in the day when he used to do this with his brother and father. Before they were hanged by conspirators trying to take over Florence and removing the problem of the Auditore Assassino that kept spoiling their plans.
End Fight, which was inexplicably excluded from the official soundtrack.
Sanctuary, a poignant and beautiful piece that plays through-out your time in Venice, that perfectly portrays the triumph and heartbreak Ezio must feel being an Assassin.
Hell, let's just say EVERYTHING in Venice, including Dream of Venice. Combined with the Scenery Porn, it makes it probably the most enjoyable city in the entire game.
One piece of music which is truly lovely is "Peace at Forli" which first plays when Ezio and Leonardo sail from Forli for Venice and then memorably plays during Ezio's "World of Cardboard" Speech in the Bonfire of Vanities DLC and then finally makes a stirring comeback in Assassin's Creed Embers playing during Ezio's final moments and the letter he left behind. It's Tear Jerker music at its finest.
Revelations gives us "The Forum of the Ox", which plays while you're jumping across ruined ledges to chase a boat over deadly rapids. Truly an Assassin's Creed moment.
Revelations has "Laboured and Lost", which plays during the game's ending, showing the end of the First Civilisation. It's truly a powerful moment and the music just heightens that. Its awesomeness must be seen to be believed.
The main "Welcome to Constantinople" music is incredibly melodious and light, a sense of serenity, hope and new horizons all at once, which captures Ezio's feelings in Istanbul and his late age..
"The Revelations theme" is worth a mention. Soft, sombre, and haunting for the main part; turned dramatic and powerful by the end!
III gives us "Trouble in Town", the angsty, turbulent music which plays during the Boston Tea Party, and when you are chasing Charles Lee. The mission is That One Level at Full Synchronization but if you time it right, its the ultimate chase music for the ultimate chase sequence. It also plays during the credits. There's also "Fight Club", catchy and fun.
The Homestead theme from III captures the solitude, peace and beauty of the settlement in the forest and also sounding like a mix of Native American and European themes, without being either, symbolizing the harmony which sadly never happened.
IV gives us the delightfully Pirates of the Caribbean-esque triumphant boarding themes among many others.
Of particular note is "Stealing A Brig", which is played when you first take the Jackdaw and during the fight near the end with Bartholomew Roberts.
Black Flag is filled with numerous actual sea-shanties that you can collect on land, including favorites like "Drunken Sailor", "Spanish Ladies" but also obscurities like "Randy Dandy Shanty". These shanties can be played by Jack, one of your crew, like the 18th Century version of GTA Radio and when sailing in rough weather, truly makes the game a magical experience, making you bond with your crew and the surroundings and feel the excitement of being part of the Wooden Ships and Iron Men generation. Especially "Fish in the Sea" when played in a rough gale or in a storm:
The tavern songs that are played by a live crew with violins and old guitars are lovely. "The Trooper and the Maid" and "Blow the Candles Out" are both bawdy songs. Then there's "The Parting Glass", a traditional Scots-Irish folk song played at the end which sums up Edward's entire journey and the game.