Many people got problems with finding the feathers, i hope this can help a bit out!
If you allready started too collect feathers and you dont know exactly where you missed one, or if you want to check the feathers! Simply press start, go to DNA and look to feathers, there you see the city's and the districts, where you can check the feather stats!
Feather map florence:
Feathers in the San Marco Distric
On top of a rooftop crane across the street from the Palazzo Della Signoria.
On a beam on the wall above a tailor’s storefront.
On a beam sticking out the east wall of a partially crumbling building.
Hidden just under the northwest edge of Santa Croce’s roof.
At the corner of some scaffolding atop a ruined building.
In front of a window overlooking a little courtyard.
On top of the scaffolding above yet another ruined building.
Above: Actually, that’s pretty hard to see…
Above: Ah, much better
On a beam jutting out from the east side of a three-story building.
Floating above a door at the north end of the Ospedale Degli Innocenti’s west wall.
Feathers in the Santa Maria Novella District
On the rooftop directly to the east of the dome on San Lorenzo.
On top of a decorative archway.
In front of a third-story window on a house just north of the Mercato Vecchio.
On a covered statue standing on a pillar at the center of the Mercato Vecchio.
Hidden in front of a rose window at the top of Santa Maria Novella’s southern facade.
In front of a small, easily accessed window.
On a beam overlooking the water, which can be easily spotted by looking west from the bridge.
On a beam sticking out of the inside of Florence’s city wall. This one’s a little tricky – you’ll need to run up the wall and jump sideways from each of the lower beams to reach it.
On top of a beam jutting out from the city’s northwest wall, just before it bends northward.