From the beacons used by the Late Romans to signal naval raids on the Litus Saxonicus in Britannia, to the lighthouse on top of the old majestic imperial palace in Constantinople, fire was widely used for navigation or signaling purposes during the Late Antique and Early Medieval periods. Today, despite the very few sources at our disposal, we are going to explore the importance of such vital and versatile structures during these historical eras.
The presence of tower-like structures in harbors with beacons on top of them is attested from the beginning of history. From the poems of Homer to the wooden lighthouses of the Phoenicians or the magnificent lighthouse of Alexandria and the beacon of the Piraeus in Athens, lighthouses and fires have always been there to guide and warn sailors or signal a potential threat and act as “sentinels”.
In the Late Antique period, “civilian” lighthouses probably manned by public slaves (Servi Publici) continued to be used in ports for navigation and signaling purposes. With the militarization of the Late Empire, a good of portion of them was fortified and systematically employed for military aims like warnings against sea raids and land attacks. An example of this militarization process is the Eastern Roman beacon system instituted in the 9th century after the Muslim Arab invasions of the Near East, made up of a system of fortified beacons that ran from the Anatolian frontier area and the Mediterranean and Black Seas to the lighthouse of the imperial palace in Constantinople. Similar methods of military signaling were employed by the Medieval Commune of Rome and the Anglo-Saxon kingdoms of England. Even Dante Alighieri, in his monumental Divine Comedy, describes the use of watchtowers as lighthouses/beacons during a sudden enemy raid.
Lighthouses in the Byzantine world were also employed as signaling beacons on top of island fortresses/mountains (mostly located in the Aegean Sea) to signal military fleets the presence of a potential stopping base, or as defensive structures/towers built on top of military citadels. The basic “Byzantine” model of a fortified lighthouse was that of a wooden tower surrounded by a wall, like the one known as Maidens Tower built at the entrance of the Bosphorus by emperor Alexius Comnenus in 1110. This lighthouse could also function as a watchtower.
As time passed, due to the frequency of Saracen/Nordic piratical raids, many coastal lighthouses of Early Medieval Europe were gradually transformed into watchtowers that also functioned as lighthouses manned by soldiers or were incorporated into monasteries or nunneries like the medieval lighthouse of the city/fortress of Gaeta in Southern Lazio (managed by nuns and incorporated into the ducal palace) or the ones in the islands around Ireland (manned by monks).
Another function of building lighthouses was to simply showcase wealth and power. As a matter of fact, differently form the “simpler” Eastern Roman military ones, the Maritime Republics of the Italian peninsula who mostly flourished due to the contacts with the Eastern Roman Empire, opted for more “monumental” and classically-inspired lighthouses, mostly located on little island/rock formations/promontories at the beys where their ports were located. These more “monumental” lighthouses, often financed by the cities’ mercantile elites, acted primarily as beacons for navigation. Examples of these are the Fanale dei Pisani in the port city of Livorno or the Lanterna di Genova, built in 1128.
To sum up, building versatile tower structures was common practice during the Late Antique and Early Medieval periods. These lighthouses had three main purposes: military signaling, navigation guiding and power showcasing. From Late Roman Stationes and Burgi along the militarized frontiers of the Empire to the “urban” towers of powerful families in Medieval Rome, Bologna or Lucca and the minarets/lighthouses/beacons built all over Europe and the Levant, towers played a central role in Late Antique and Medieval society.