here is some maps to get you started
IGN's map
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http://uk.ign.com/wikis/assassins-creed-revelations/Animus_D...Gamesradar's map
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http://www.gamesradar.com/assassins-creed-revelations-data-f...After you have collected half of the fragments (50) the game adds the locations of the ones your missing to your map.
(and once on the map you can put a marker on them for ease of locating)
Don't forget about the Cappadocia location you have to get some from.
To get there you take the ferry in the southeast corner of the upper island. This will allow you to return to the underground city of Cappadocia.
Credit to DaFonkster87 for telling me about GR's Map