The simple preposition a in Italian has a multitude of uses. The preposition a is often used before particular cities or places:

a Roma

a Firenze

a Berlino

but in Toscana1

The following places and locations are also used with the preposition a:

a casa2 at home

a letto in bed, to bed

alla stazione at the station

Note that almost all the simple prepositions - except per and fra/tra - combine with the definite article.