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Elegant and imposing at the same time, the Castle dominates the whole Tiber Valley.
Reconstructed in the 16th century on a pre-existing fortress, has a square plan, with towers at the four corners. Inside there's a beautiful renaissance courtyard with a double gallery, on which various precious rooms are facing. One of them is the chapel with 17th century good frescoes, to be considered a sort of visual memory of the history of Alviano.
In the chapel is actually depicted the miracle of St. Francis and the swallows, which happened at Alviano - "...he began preaching, ordering first the swallows who were singing, to keep silent... " (Fioretti) but we can see also Donna Ohmpia's face because she was the one who commissioned the fresco. It's a contemporary work instead the portrait of Bartolomeo we see in the Council Hall; the features are the real ones, taken from a 16th century coin, struck by the Republic of Venice.
Even now the Castle, well restored, is the centre of the urban life: the "piano nobile" houses the Municipality; on the ground floor is the audiovisual documentation Centre of the Oasis of Alviano, and a modern and equipped Meeting Centre; in the basement are permanent exhibitions of modern art and the Museum of Agricultural Civilization, which can boast over 1,000 exhibits.
Recently, to honour its ancient lord, the Castle has been made the seat of a Study Centre about mercenary captains.
Inside the town centre is the Parish Church of Santa Maria Assunta (15th cent.).
Documented as "Collegiata" since 1275, in the beginning of the 16th century was adorned with a precious tablet by Nicoḷ Alunno, depicting Our Lady of the Assumption surrounded by glorifying angels.
It had previously two side panels with St. John the Baptist and St. Sebastian now at the National Museum of Castel S. Angelo in Rome.
There is also a very interesting fresco by Giovanni Antonio de' Sacchis, named "il Pordenone", commissioned by Bartolomeo d'Alviano's widower, Pantasilea Baglioni and showing herself among the Saints aside the Virgin.

Environmental sights

The entire southern ridge of the Amerini mountains, from Baschi to Amelia, but especially at Alviano, is characterized by a very neat geographic feature: the gullies.
They are a very important geological peculiarity, with significant rellcs of the ancient "mare tiberino", and a fundamental contribution to the agricultural history of this land.
The landscape is peculiar and clearly characterized by the cultivation of the olive tree.