While the bishopric has been established since at least the 4th century, the present Acqui Cathedral building was begun under bishop Primo (989-1018) and was consecrated in 1067 by bishop Guido. The ground plan is in the shape of a Latin cross, and there are five aisles (but until the 18th century, only three), terminating in three semi-circular apses. Of the Romanesque structure there still remain visible the apses, the transept, and the crypt, which underlies both the transept and the choir. The remainder has been subject to further work in later centuries.
The terracotta bell tower was finished in 1479, and the bells moved from the old campanile. The main entrance in marble, by Giovanni Antonio Pilacorte, dates from 1481, and the rose window above it from around the same date, while the portico is 17th century. The interior was re-fitted in Baroque woodwork, and was decorated with frescos and stucco work from the 17th to the 19th centuries.
Next door are the canons' cloisters of the late 15th century, and some Roman ruins.
The 19th century pulpit and the Baroque altar of Saint Guido in the transept are worthy of note. The most important work of art in the cathedral by far however is the triptych of the Madonna di Montserrat, the Annunciation to the Virgin of Montserrat, the work of the 15th century Spanish painter Bartolomé Bermejo, in the chapter house.
References:The Walls of Constantinople are a series of defensive stone walls that have surrounded and protected the city of Constantinople (today Istanbul) since its founding as the new capital of the Roman Empire by Constantine the Great. With numerous additions and modifications during their history, they were the last great fortification system of antiquity, and one of the most complex and elaborate systems ever built. They were also the largest and strongest fortification in both the ancient and medieval world.
Initially built by Constantine the Great, the walls surrounded the new city on all sides, protecting it against attack from both sea and land. As the city grew, the famous double line of the Theodosian Walls was built in the 5th century. Although the other sections of the walls were less elaborate, they were, when well-manned, almost impregnable for any medieval besieger.