626 ancient stonemason marks reveal how the gate of Greek Ptolemais in Libya was built

Ancient marks carved into the limestone blocks of the Gate of Tauchira in present-day Libya have given archaeologists a rare look at how one of the best-preserved Hellenistic fortifications in Cyrenaica was built more than 2,000 years ago. A new study identified and analyzed 626 stonemason marks, revealing how work crews organized construction, how the project was funded, and when the gate was likely completed.

The Gate of Tauchira formed part of the defenses of the ancient city of Ptolemais. Although travelers recorded the strange carvings as early as the 18th century, no detailed study had examined them until now. Archaeologist Anna Urszula Kordas of the University of Warsaw documented every visible mark and sorted them into 27 different types.

The marks acted as a record left by the workers who cut, moved, and placed the stone blocks. By mapping where each mark appeared, Kordas reconstructed the sequence of construction from the quarry to the finished gate.

Two clear groups of marks emerged. The first appears on unfinished blocks facing the city’s interior. These large, uneven symbols were often upside down, showing they were carved before the stones reached their final position. They likely helped crews track blocks during quarrying and transport.

The second group appears only on the rusticated outer walls of the towers. These marks are carefully carved, centered on the finished stone surfaces, and always upright. Their position shows they were added after the blocks were placed and shaped. Unlike most Greek and Hellenistic buildings, where such marks were hidden or removed, the builders of Tauchira left them visible on purpose.

The symbols also point to two different ways of organizing the work. One system used letters of the Greek alphabet, including A, B, Gamma, Delta, E, Zeta, and Eta. These letters appear in sequence and likely marked at least seven separate construction teams.

A second system used monograms made from two or more letters. These more complex signs probably identified individual stonemasons, workshops, or wealthy sponsors. Their presence beside the alphabetic marks suggests public contracts worked alongside private support. Wealthy citizens may have financed part of the project by supplying crews through voluntary donations, a practice known in the Greek world.

The distribution of the marks also shows the gate’s two towers rose at the same time instead of one after the other. Most symbols appear on only one tower, while a few occur on both, showing several teams worked in parallel. Some marks continue from the lowest preserved courses to the highest, suggesting construction moved quickly without long breaks. The nearby limestone quarry, only about 500 meters away, also helped speed the work because blocks could be transported before final shaping.

The study offers fresh evidence for dating the monument. Earlier estimates relied mostly on historical comparisons. Kordas examined the shapes of the engraved Greek letters and found features common in the second century BCE. An early graffito inside the gate matches the same writing style and supports this time frame.

Together, the evidence points to construction or a major remodeling during the reign of Ptolemy VIII Physcon, who ruled Cyrenaica between about 145 and 116 BCE. The proposed date also matches a period of strong building activity across the region.

The study documents at least seven lettered work teams and another 14 groups or individuals identified through monograms. Some blocks even carry two marks, showing different workshops worked on the same stone. These carvings preserved far more than names. They recorded the pace of construction, the movement of materials, the structure of the workforce, and the mix of public and private funding behind one of North Africa’s best-preserved Hellenistic gates.