Surmounted by a portrait head of Alexander the Great, this herm features a highly polished and sensitively carved face with lidded, almond-shaped, articulated eyes. His full lips curve into a slight smile, while his wavy, leonine locks, arranged in his characteristic anastole hairstyle, are bound by a fillet. The head is set atop a smooth shaft that tapers slightly towards the base, with genitalia and toes sculpted in high relief.
As C.C. Mattusch notes (p. 179 in Pompeii and the Roman Villa: Art and Culture Around the Bay of Naples), herms served a variety of functions in antiquity. In the Greek world, herms (named for Hermes) were primarily apotropaic in nature, serving as protectors of travellers, cities and homes and were placed on street corners, doorways and other boundaries. In the Roman era herms came to be adorned with portraits of poets, philosophers, statesman and other deities where they were used as decorative adjuncts in niches or mounted around pools and gardens.
The sculpting of the sides and back of this example suggests that it was most likely part of a boundary surrounding a pool, garden, or stadium, with the head facing inward.