The District of Piazza al Serchio is in the province of Lucca, in a valley called Garfagnana. As it lies in the north   of the chief town province, from which it is about 60 kilometers away, the District is only 20 kilometers from the province of Massa Carrara.
The District territory extends for 27,08 kilometers and it borders on the districts of Minucciano, Giuncugnano, Sillano, Camporgiano, and San Romano. It is crossed by the Serchio river which, in the small town of Petrognano, begins its main flow thanks to the Acquabianca river, which joins the Serchio river coming from Sillano.

Since it lies in a mountainous area between the Apuane Alps and the Appennino Tosco-Emiliano, it is really rich in woods. The average altitude of the District is 535 metres above the sea level. The climate is generally mild although temperatures go down in winter and it snows very frequently. As far as precipitations are concerned, it mainly rains during Spring and Autumn.

At the moment the District territory involves the small towns of San Michele, Nicciano, Cortia, Gragnana, Colognola, Sant’Anastasio, Petrognola, Cogna, Borsigliano, Livignano, Vergnano, San Donnino and Petrognano, not including the chief town.
From a geographic point of view, the town lies at 44° 11' 07" north latitude and at 10° 17' 52" of longitude west

According to the survey of October the 17th 2005, the population consists of 2508 inhabitants ( 1212 males and 1296 females per 940 families), with a density of 92 inhabitants per square kilometres.