Piazza Guglielmo Marconi, known as “Platea Sanctae Mariae” during the Medieval age, probably coincides with the ancient Platea Maior. The gate with two arches that leads into it (called Cubic Gate or Square Arch), marked the highest and nobler part of the town, the so-called Arce or Acropolis, typical of the Etruscan and Umbrian towns, that were usually fortified and represented the monumental entrance of the town. Of the original structure the internal arch remains (2nd – 1st century BC), the one that faces out on the square, made of big travertine squared blocks.

A monumental fountain leaned against it and it was replaced with the church of Santa Maria di Porta, of which only the doorway remains (at street number 2). The external arch, instead, is considered much more recent and it probably dates back to the Imperial age (1st – 2nd century AD). It has a round barrel vault and it is decorated with marble inserts. Between the two arches, there is a barrel vault gallery and on the left sidet, we can see a painting representing the Virgin with Child made by an anonymous painter of the 15th century.

In later times, this spot had other names: during the Renaissance it was called Piazza Grande until the Unification of Italy when it was newly dedicated to King Victor Emanuel II. Later it was commonly called “Piazza della Posta” (Post Office Square) for the ancient papal postal station hosted here since the 18th century: of this period, the square still conserves the paving stones separated by rows of terracotta bricks. For a small period the square was also called Piazza Petrignani because of the palace bearing the same name that rises up here and that stands out against the other buildings with its high and imposing facade.

Town Crier’s Arcade and Nacci Palace In the square, in addition to the Cubic Gate and Petrignani Palace, we can see some of the town’s most important buildings. On the short side to the left, there is the charateristics Town Crier’s Arcade: from the vantage stand reachable through a double flight of stairs, the town crier, or Herald, made public announcements to the call of a trumpet. On the stairway stands a column with a Doric capital that was erected in 1479 in honour of Stefano Colonna who committed to the municipality of Amelia, the jurisdiction on the town of Penna in Teverina, an ancient feud that belonged to Colonna family.

A public clock built during the 18th century is on top of the arcade. The Nacci palace, situated on the corner of Via del Duomo and Via Garibaldi, originated in 1342 by joining together three seperate Medieval tower dwellings and taking advantage of the arched vaults of the 13th century market as a support. The entrance is on the opposite side, in via Carleni and it consists of a sculpted doorway with an inscription bearing the name of its former owner “Hippo Naccius”. The interior has a harmonius courtyard with an elegant stairway leading to the arcade with finely carved columns and capitals.