Geometry, Shape, and Typological Adaptation of Lighthouses Within the Italian Environment

Geometry, Shape, and Typological Adaptation of Lighthouses Within the Italian Environment

Giuseppe Amoruso (Politecnico di Milano, Italy)
DOI: 10.4018/978-1-5225-3993-3.ch015


The chapter starts from the analysis of several buildings designed as lighthouses for the Italian network or adapted to host lights from existing heritage. The graphic study of shapes, internal staircases, and also architecture creates an important reference for morphogenesis studies. The chapter presents the evolution that lighthouses have undergone during the centuries in order to assume geometrical layouts; while the outward appearance of the tower has always been designed according to their visibility during the day hours, shape and construction's technology evolved through geometrical forms which would resist to the conditions of exposure and to critical state of the site. The interior staircase represents the living core starting from stone design and cutting, according to the stereotomic design. The chapter presents a parallel of cases, highlighting geometric principles, shapes, and solutions according to architectural typology.
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Lighthouses are most popular architectures designed according to technical and functional issues for navigation, orientation and safety of sea travelers. They are the result of a long and slow process of adaptation to natural site and diverse weather and landscape conditions taking advantage of local materials and exposure; their typological character combines construction technologies, proportions among their parts, details and lighting requirements. Their construction deals with weight and lightness, with gravity and combination of several stresses and forces which inform their geometry and shape.

Lucien Steil in the Metaphysical archeology of lighthouses or a phenomenology of lighthouses argues that:

they are not simply built into the landscape but the landscape exists because of them... They are catalysts of their context: they invent the patterns of their immediate and larger environment, and in the same time they result from the inspirational sources of the genius loci. (Steil, 2005, 26)

Free standing architectures designed to be operated both during day that night: by day appear clearly in their entire silhouette and engage attention through their solidity, color texture, domination and strength. They mark a strong presence to preserve landscape and built environment, witnesses of the challenge of the man on the nature; by night architecture loses its material appearance and yields the step to the light, an intermittent, escaping, contrasted bundle.

Modern navigation technology advances have largely rendered obsolete the functional retrofitting of lighthouses in Italy but their extraordinary typological and symbolical connotations resume highly valuable potentials to justify their analysis.

Lighthouses are built obviously in appropriate and significant locations, on coastal heights, islands, rocks and eventually right into the sea onto artificial islands. They guide, warn, mark, alert, lighten and highlight dangerous areas, complex obstacles and entrances to harbors, city ports and shallow estuaries, etc. their expressed purpose is to carry light in the most remarkable and visible manner so that even distant ships can be warned or guided, and that even, throughout the darkest nights, through the most opaque and starless universe, heavy storms and fogs, the lighthouse's warm and familiar signals can be perceived. (Steil, 2005, 32)


The Genesis Of The Italian Network And The Evolution Of Architectural Types

The analysis of the ancient iconographic sources allows to highlight the evolution that lighthouses undergone during the centuries in order to assume geometrical configurations or to adopt technological solutions which made them more resisting to wind, sea, and above all, time actions. While the outward appearance of the towers has always been conditioned by the improvement of their visibility during the day hours, shape and construction’s technology evolved through geometrical forms which could resist to the conditions of exposure and to the critical state of the site. (Amoruso, 2005, 79)

The Italian network of maritime signallings stretches along the diverse coast environmental conditions of our peninsula, major seaports and islands, totaling 824 navigation supports, which include 157 lighthouses and 667 lights (including seamarks and buoys).

Key Terms in this Chapter

Fresnel Lens: It is a type of compact lens originally designed by French physicist Augustin-Jean Fresnel for lighthouse optics. It’s the most important part of a lighting devices consisting of a convex lens and many glass prisms that concentrate and intensify the light into a horizontal beam.

Light Position: The distance measured from the beacon geographic height to the centre of the lens or optics.

Aerobeacon: A type of beacon present in many lighthouses to produce a specific characteristic for the purpose to aid aerial navigation and used when the light is close to airports or along aerial routes.

Spiral Staircase: This is the type of stair most frequently used in lighthouses to climb up to the lantern room or to the watch room. It is accommodated into cylindrical (or tapered cone) towers.

Regency: Headquarters, facilities, and keepers who are responsible of a series of beacons and/or lighthouses.

Beacon: A signalling or guiding device part of a network of aids, such as a lighthouse or a small freestanding one. They are used at the harbour entry or in presence of harbour works, danger for safety of navigation and point on the coasts with secondary interest. They are designed with different standard colours, white, red, green, or yellow and/or texture patterns, depending on the light’s function.

Keeper: The person in charge for the maintenance of the lighthouse technical devices. In many lighthouses keepers have headquarters and they are accommodated with their families.

Range: The longest distance from which a light beacon or a lighthouse is visible (from the sea), depending on its characteristic, luminous intensity and meteorological visibility.

Lantern Room: It houses the electric and optics devices at the top of a lighthouse tower; usually has a cylindrical shape but it is common to find also polygonal rooms.

Gallery: The lighthouse tower is composed, over the top, by an outdoor walkway or balcony that makes accessible the lantern. Gallery features the lighthouse because it can be built in masonry and whitewashed or have a metallic railing with stairs for glasses maintenance.

Tower: The architectural or functional structure supporting the lighthouse lantern.

Daybeacon: A beacon which provides the mariner, through its shape and texture, with navigation information during daylight hours.

Lighthouse: It’s the main signalling system for the navigation aid and it’s a fixed beacon usually emitting a white light to help the mariner identify a geographic location or a danger. Lighthouses are usually built according to different architectural issues and land conditions; they can be part of an existing heritage building and also characterized by their unique colour pattern and decoration.

Watch Room or Service Room: A room that serves and makes accessible the lantern room; it’s also a place for watch, used as a repair workshop or to store supplies. Sometime the room is hosting the clockwork apparatus for rotating lenses or other devices to fuel the mechanism in case of electrical black out or lack of energy.

Typology or Architectural Typology: It’s a combination of building, geometry and layout features characterizing a lighthouse. It includes the classification of architectural elements for structures (masonry or concrete frame or steel trellis), materials (brick, stone, steel, etc.), and geometric patterns and decoration.

Order: According to the characteristics of the Fresnel lens or simple lenses, which determines the brightness and distance the light will travel, order features each lighthouse. Lens order ranges from first to sixth, the smallest lens and it is related to the Focal length of the lens (mm).

Lamp: It is the electric device which produces light and it is places inside the lens.

Optics: The electrical and lens devices used to produce the light pattern in a lighthouse.

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