The Tower of the Winds, also known by other names, is an octagonal Pentelic marble tower in the Roman Agora in Athens, named after the eight large reliefs of wind gods around its top. Its date is contested, but was by about 50 BC at the latest; it was mentioned by Varro in his De re Rustica of about 37 BC. It is "one of the very small number of buildings from classical antiquity that still stands virtually intact", as it has been continuously occupied for a series of different functions.
Formerly topped by a wind vane, it is the only surviving horologium or clock tower from classical antiquity. It also housed a large water clock and incorporated sundials placed prominently on its exterior faces; "citizens were thus able by using this building to orient themselves in space and time. Architecture, sculpture and the new science were perfectly integrated".
According to A. W. Lawrence, "the originality of this building is exceptional, and of a character out of keeping with Hellenistic architecture as we know it ... the design is obviously Greek, both in the severity of decorative treatment and in the antiquated method of roofing. The contrast with work of the Roman Empire is extraordinary, considering the date", which is long after the Roman conquest of Greece.
Names
The English name Tower of the Windspersonified on the building as the Anemoiis ultimately a calque of the ancient Greek name Pýrgos tōn Anémōn (). It has also been known as the Horologium (Latin) or Horologion (, Hōrológion), from hṓra (, "time period, hour") lógos (, "writing, recording") + -ion (), together usually meaning a sundial, clepsydra, or other timekeeping device but here used to describe the location housing them.
It is now known in Greek as the "Winds" (, Aérides) and as the "Clock of Cyrrestes" (, Orológio tou Kyrrístou).
Design
Raised on three steps, the Tower of the Winds is tall and has a diameter of about . In antiquity it was topped by a bronze statue of a Triton, holding a rod that acted as a weather vane indicating the wind direction. Below the frieze depicting the eight wind deities—Boreas (N), Kaikias (NE), Apeliotes (E), Eurus (SE), Notus (S), Livas (SW), Zephyrus (W), and Skiron (NW)—there are eight sundials. A cornice above is decorated with lions' heads in relief, functioning as water spouts.
Inside, there is a single large room. From ancient mentions by Varro and Vitruvius, it seems that time was measured by a water clock, driven by water coming down from the Acropolis. There are holes and channels in the floor relating to this, but the mechanism, presumably of metal and wood, has gone. Research has shown that the considerable height of the tower was motivated by the intention to place the sundials and the wind-vane at a height visible from the Agora, effectively making it an early example of a clocktower.
It had two porches with pediments, supported by two Corinthian columns at the front, now disassembled, though the lower parts of three columns remain in place. These columns had capitals of a design now sometimes known as "Tower of the Winds Corinthian", a "late variant form" lacking the volutes ordinarily found in Corinthian capitals. There is a single row of acanthus leaves at the bottom of the capital, with a row of "tall, narrow leaves" behind. These cling tightly to the swelling shaft, and are sometimes described as "lotus" leaves, as well as the vague "water-leaves"; their similarity to leaf forms on many ancient Egyptian capitals has been remarked on.
To the rear a "turret" held the water for the clock. The main roof is essentially original, with 24 triangular stone slabs, carved on the outside to look like tiles; here rows of modern standard rounded roof tiles now cover the joins. Inside eight very small columns, less than four feet high but with richly carved shafts, stand at each corner of the octagon, on a circular cornice, running up to a circular architrave.
Functionality
Andronicus of Cyrrhus, the designer, seems to have written a book on the winds. A passage in Vitruvius's chapter on town planning in his On Architecture (De architectura) seems to be based on this missing book. The emphasis is on planning street orientations to maximize the benefits, and minimize the harms, from the various winds. The London Vitruvius, the oldest surviving manuscript, includes only one of the original illustrations, a rather crudely drawn octagonal wind rose in the margin. This was written in Germany in about 800 to 825, probably at the abbey of Saint Pantaleon, Cologne.