The Sampietrini Roads of Rome

By Jenny Osburn

Note: All photos by author, unless otherwise stated.

Intro

The iconic roads of Rome, both narrow and paved by mesmerizing cobblestones. These Roman roads are quite unique, and in stark contrast to those I’m used to seeing in the United States. In the US there is a distinct separation between the road and the sidewalks; the roads are wide, uniform and generic; and are made of either asphalt or concrete. It is true that some of Rome’s busy roads follow this design, of being large and using asphalt, but the roads I am studying here are specifically the cobblestone ones. These cobblestone roads in Rome, in contrast, are used by both pedestrians and motor vehicles alike; for the most part do not offer protection for the pedestrians; they are located tightly between buildings; and the cobblestones can be arranged in different patterns. To help visualize, see Figures 1 and 2 below.

This paper will discuss what the sampietrini are, provide a brief history of them, consider from an engineering aspect how they impact Rome today in terms of construction, maintenance, and performance, and conclude with what the community thinks of them.

I. The Sampietrini

The cobblestones are locally called “sampietrini”, or alternatively “sanpietrini”. This name comes from the origin of their use, Piazza San Pietro, which in English is Saint Peter’s Square (“Cobblestone inspiration from the streets of Rome,” 2020). This origin story will be covered more in the next section. 

The design of the sampietrino stone is fascinating. Sampietrino stones are made of basalt, which is a very hard and dense form of volcanic rock. This makes the material quite durable, and able to last under vehicle loads. These stones were mined from the quarries around Rome, near the Alban Hills and Viterbo (“Sampietrini: the story of Rome’s iconic cobblestones,” 2024). After the basalt is mined, the stones are hand cut. When it comes to their individual shape, it is quite different than one might originally think, if only observing them from above. As seen in Figure 3, their top and bottom surfaces are square, but their vertical cross section resembles the shape of an inverted isosceles trapezoid.

The mesmerizing part about roads of sampietrini is that they can be so unique. The sampietrini come in a variety of different sizes, as seen in Figures 4 and 5. The shape is nearly always a square, with the largest being 12×12×18 cm and the smallest ones at 6×6×6 cm. The most commonly used ones are 12×12×6 cm (Mohora and Anghel, 2019). The sampietrini furthermore can be arranged in many different patterns. The common ones are repeating arcs and a 45 degree herringbone, as seen in Figures 6 and 7, respectively.  

II. A Brief History

Roman roads have quite a long and ancient history, but the origin of the sampietrini roads occurred during the late 16th century. It was during this time, specifically 1585, that Pope Sixtus V had St. Peter’s Square and the nearby area re-paved using cobblestones, to replace an existing damaged road which was problematic for carriages (“Cobblestone inspiration from the streets of Rome,” 2020). This, as mentioned before in the previous section, is the reason why the sampietrini are named after Saint Peter’s Square. For a clear picture as to the many sampietrini used in the square, at least presently, see Figure 8.

It is important to note that while the origin of the sampietrini occurred in the 16th century, it surprisingly wasn’t until the 18th century, when the use of sampietrini as the paving material of roads spread to many other parts of Rome. This happened during the time of Pope Clement XII Corsini, and his work at expanding building operations in Rome (“Sampietrini: the story of Rome’s iconic cobblestones,” 2024).

These days the sampietrini roads are mainly only present in central Rome, as seen in Figure 9. The main outlier in Figure 9 is the Via Appia Antica, which I had the pleasure of viewing during a bus trip to the catacombs just outside of the city. From observation of Via Appia Antica, though small and skinny, it still seemed like it was in good working order, as you may notice in Figures 10 and 11.

This diminishing amount of pure sampietrini streets comes down to two slightly different uses of asphalt. Firstly, how in 2005, the Roman city council decided to replace some busy and heavily trafficked cobblestone streets with asphalt instead, due to hazardous conditions and maintenance costs (“Rome Trading Cobblestone Streets for Asphalt,” 2005); these conditions and costs will be described in later sections. And similarly, by how some sampietrini streets were paved over, like an overlay, with asphalt.

Engineering Thoughts

I. Construction Process

The method of paving roads in sampietrini is a meticulous and expensive one. As seen in Figure 12 below, there are a few different sub-base layers, in addition to the sampietrino stones. The difficult part is that the sampietrino stones must be hammered into the sand-base layer with a mallet; making sure they are all installed in a tight formation, and at roughly the same height (“Cobblestone inspiration from the streets of Rome,” 2020). It is a very manual process, which requires specially trained workers, due to the precision needed. These types of workers are currently limited, which is the main reason for the increased price to pave in sampietrino (Zoccali, et al., 2017). This price is in fact four times greater than the price to pave in asphalt, at 200 € per square meter for Sampietrini pavement and about 50 € per square meter for asphalt concrete (City of Rome as cited in Zoccali, et al., 2017).

A few variations in the bedding course, which is the material placed between the sampietrino stones, are permitted. I have often seen the materials be sand or asphalt, as seen in Figures 13 and 14; but concrete is also a viable option. The decision of which bedding course to use, comes down to how strong and sturdy the road needs to be designed for against vehicular traffic.

II. Roadway Projects & Maintenance

I have been fortunate enough to see some road work projects take place; in fact, one in front of my own apartment, as seen in Figures 15, 16, and 17. It is quick and easy, but still meticulous, to perform this work on roads paved in sampietrini. When I say quick, I really mean quick; small sections were each enclosed by fences and the work completed took roughly two days. And by easy, I mean that the sampietrini stones can be taken out and simply set aside, then a hole dug in the sand/soil sub-base, followed by completing the necessary project work. After that task is complete, the same sampietrini stones can either be reused and reinstalled, or the area can be instead be covered in asphalt or concrete. 

III. Performance

Positive

The sampietrini streets which utilize soil and sand as a bedding course, have two positive performance-qualities. Having an absorbant and penetrable material such as soil and sand between the sampietrini, allow for drainage of excess water down through the sub-base layers and to the ground water. This is helpful considering Rome’s water and sewage system can reach capacity at times. Also helpful, is that the sampietrini within the sand and soil are able to move with the earth. This is beneficial when the earth has slight shifts due to volcanic activity (“Cobblestone inspiration from the streets of Rome,” 2020).

Issues

When wandering the streets, it is quite common to see a damaged section or two in the sampietrini. The damage and disruption starts off slow, with one sampietrini uneven and sunk into the road surface (Figure 18). After some time and wear however, this radially expands to three or four additional stones loose and askew (Figure 19). This can even lead to the extent of stones getting displaced and missing out of the ground (Figure 20). These are all performance issues for cars, scooters, and walkers alike.

There are also issues prevalent during heavy rainstorms. The sampietrini with asphalt as the bedding course, once slightly wet as seen in Figure 21, can become slippery and dangerous. Furthermore, the use of asphalt as a binder between stones, lack of proper drainage, and dips in the sampietrini can create large puddles, which are certainly a nuisance and issue for pedestrians and scooters (Figures 22 and 23).

Finally, what’s not as noticeable of an issue, is there are certain cases when the sampietrini can create loud noises, resulting in vibrations. This happens mainly when large and heavy vehicles, such as buses and trucks, drive on top. These are quite harmful, not to the surrounding people present, but rather to the local buildings. As NBC News put it, 

Maurizio Galletti, an official at the Culture Ministry responsible for Rome’s architectural heritage, said the vibrations had damaged some of the city center’s grand Renaissance palaces and caused small fissures in the frescoes that adorn their interiors. (“Rome Trading Cobblestone Streets for Asphalt,” 2005).

Conclusion

The sampietrini roads of Rome are certainly unique, and a jewel to see and experience. Both locals and tourists appreciate them for their ties to history, and their pleasant appearance and aesthetic. They are also ideal in that after being taken out for maintenance work they can be reused, and that when utilizing sand and soil as the bedding course, the sampietrini provide drainage of excess water and are able to slightly move with the earth. It is certainly true however, that they have their drawbacks; from construction being a great deal of money and effort, to prevalent pothole and drainage issues impacting vehicles and pedestrians, and excess vibrations causing damage to buildings. It makes sense therefore, for Rome to have both roads paved in sampietrini as well as modern roads paved in asphalt, and that they lessened the amount of sampietrini ones. With the use of both, and the asphalt ones being used in areas with high vehicle traffic and speed, a nice balance can certainly be achieved.

References

“Cobblestone inspiration from the streets of Rome.” Artisan Exterior, 13 Jan. 2020, https://artisanexterior.com.au/explore/cobblestone-inspiration-streets-rome.

Mohora, Irina, and Anamaria Andreea Anghel. “Urban Landscape- Cubic Stone Streets in Historical Areas, Advantages and Disadvantages, Case Study Timisoara Versus Rome.” IOP Conference Series Materials Science and Engineering, vol. 471, 2019, doi:10.1088/1757-899x/471/8/082028,https://www.researchgate.net/publication/331314079_Urban_Landscape-_Cubic_Stone_Streets_in_Historical_Areas_Advantages_and_Disadvantages_Case_Study_Timisoara_Versus_Rome.

“Rome Trading Cobblestone Streets for Asphalt.” NBCNews, NBCUniversal News Group, 25 July 2005, http://www.nbcnews.com/id/8700967/ns/world_news-europe/t/rome-trading-cobblestone-streets-asphalt/#.XYsBJJNKhPZ.

“Sampietrini: the story of Rome’s iconic cobblestones.” Wanted in Rome, 05 Feb. 2024, https://www.wantedinrome.com/news/sampietrini-the-story-of-romes-iconic-cobblestones.html.

Zoccali, Pablo, et al. “Sampietrini Stone Pavements: Distress Analysis Using Pavement Condition Index Method.” Applied Sciences, vol. 7, no. 7, 2017, doi:10.3390/app7070669, https://www.researchgate.net/publication/318037835_Sampietrini_Stone_Pavements_Distress_Analysis_Using_Pavement_Condition_Index_Method.