Before you start, you have to collect and decipher all 30 codex pages, so hopefully you have been collecting them as you go along or you will have a lot of travelling to do! You collect 14 of them in the game story mode, but the other 16 are scattered around - there are 6 in Venice, 5 in Florence, 2 in Tuscany and 3 in Forli.
Once you have completed this part, a short movie sequence happens and then you have to attempt to sort out the codex pages, I'm assuming this is the part you are stuck at because it can be quite frustrating trying to align the pieces. Use eagle vision first of all to see a map of the world, all jumbled up. If it helps, all pieces of codex are in the right positions, you just have to turn them, and it helps to try to sort the outline out first - all you have to do is to make sure the line around the outside of the map is lined up.
Then the harder part - arranging the middle pieces. If you can get your hands on a map of the world it will really help! Just keep trying and eventually you will get there. Start with a section of the map you are reasonably familiar with - for example South America. Hope I helped! :)
Use eagle vision to spot your target then chase her. (Not to kill, follow)
It's on the ground level of the Colosseum, near the gated area. Might want to turn on Eagle Vision for this part, as the entrance can be tricky to spot.
S Marks the Spot was created in 2008.
The duration of Spot Marks the X is 1.5 hours.
Spot Marks the X was created on 1986-10-18.
X Marks the Spot - 1942 is rated/received certificates of: USA:Approved
Spot Marks the X - 1986 TV is rated/received certificates of: Iceland:L
x marks the spot
Chef Marks the Spot - 2013 TV was released on: USA: 23 April 2013
X Marks the Spot - 1931 is rated/received certificates of: USA:Passed (National Board of Review)
During the Civil War era when they said "X marks the spot" it meant where they were going to attack or set up camp. They used this to keep their spot secrete.
you found it