Sardinian is the indigenous and historical language of most Sardinian communities. However, Sardinian is not spoken as the native and primary language in a significant number of other ones, amounting to 20% of the Sardinian population. The afore-mentioned Gallurese and Sassarese, despite being often colloquially considered part of Sardinian, are two Corso-Sardinian transitional languages; they are spoken in the northernmost part of Sardinia, although some Sardinian is also understood by the majority of people living there (73.6% in Gallura and 67.8% in the Sassarese-speaking subregion). Sassari, the second-largest city on Sardinia and the main center of the northern half of the island ("cabu de susu" in Sardinian, "capo di sopra" in Italian), is located there. There are also two language islands, the Catalan Algherese-speaking community from the inner city of Alghero (northwest Sardinia) and the Ligurian-speaking towns of Carloforte, in San Pietro Island, and Calasetta in Sant'Antioco island (south-west Sardinia).