Location of Ilaria's apartment couldn't be more perfect! Your doorstep is right across Museo Galileo, which is adjacent to the Uffizi Gallery. From this side, you can see Ponte Vecchio and the Arno River. On the opposite direction, you can walk to the Duomo, Palazzo Vecchio, Accademia and Santa Croce. All important Florence sights are within at most a 15 minute walk from her apartment. House is huge and clean! Beds, pillows and towels are soft and comfortable.
Ilaria was also a lovely host! She was very responsive and helpful, offering suggestions on where to eat in the area. We met her friend Sara who was equally lovely and friendly as she helped settle us in.
An advice to others though, do not follow the google street view as it is incorrect. Just walk a few steps down (maybe 20 steps) towards the Arno river and Museo Galileo and you will find 4 Via Castellani. Google street view shows you 4, but this is not on Via Castellani. In Florence, on a single street, street names change per block of buildings.
Overall a great experience and would definitely stay at Ilaria's apartment again. Highly recommended to anyone visiting Florence! Thanks Ilaria!