The remains of the Servian walls, also known as republican walls, dating back to the 4th century BC, are so scanty that it would not be worthwhile dedicating a real tour to their visit. Many of them appear as simple fragments, incorporated in structures built later on, or partly hidden by the weeds, often rather small and scattered through several districts.
The schematic map shown on the left features the perimeter of the original set of walls in brown colour, with the few parts still standing in red, and the gates in blue.
Nevertheless, these tiny bits still represent an important relic of the city's first real boundary, and it is also interesting to compare the many structural differences between this wall and the one built by Aurelian no less than half a millennium later.

The following is a list of city spots where the fragments can be found; the progressive numbers are consistent with the ones in the map.

At the bottom of each entry, the most important sites of touristic interest located in the immediate surroundings are also listed.

1. via Antonio Salandra

At the end of this street, a few metres before joining via Piemonte, there is a 20-metre long surviving stretch of wall. By the end of the 19th century, this remain was enough unlucky to find itself on the site of a modern crossing, and had to be cut into three parts to let the traffic through. The segment on the western side of the street, closed by an iron gate, provides an excellent cross section of the structure, which enables us to see how these large blocks were assembled together in a very simple way.

The segment on the opposite side, now covered by a porch, is the longest of the three, while the last part, on the northern side of via Carducci, ends in the wall of a building.
Just a few metres further from this spot, the brownish Aurelian's walls can be seen in the distance, closing via Piemonte at its very end.

2. piazza dei Cinquecento

The longest surviving stretch of these walls is the one on the left side of Rome's central train station, Stazione Termini. It stands in a long garden, now protected by an iron fencing.
This part of the wall represented the north-eastern part of the boundary, where an agger, i.e. earth and stones piled along the inner side of the wall, and a mound by its outer side, acted as further protections.
Other large fragments belonging to the same wall can be seen in the shopping alley below the station (in roman times, the original ground level was much lower than the present one); they have been identified as a part of the counterscarp that prevented the agger from sliding down.
Not far from here stood the northernmost gate, Porta Collina: two important roads leading to the north-east, via Salaria and via Nomentana, started from this spot (further details about these roads can be found in the section about Aurelian's Walls, northern side, page  2 and page 3.

Underground traces of the same wall are also visible by the subway station Repubblica, not far from Termini, along one of the exit corridors, but nothing is left above ground.

NEARBY MAJOR FEATURES
basilica of Santa Maria degli Angeli
remains of Diocletian's Baths

3. piazza Manfredo Fanti

In the middle of this square, in the garden in front of the Roman Aquarium (a large white building with a dome) are a few blocks belonging to the republican wall. Along its external side traces of a brick house are left, easily told by their reddish colour. When the city expanded beyond the early boundary, houses were frequently built with one side against the old wall, so that the latter would have made the new building more steady. This also happened during the late empire (4th-5th centuries) with Aurelian's wall, see part II page 2).

NEARBY MAJOR FEATURES
basilica of Santa Maria Maggiore

4. via di San Vito

This short and narrow road, which runs from via Merulana to via Carlo Alberto, is crossed by an arch of white travertine, named after Gallienus (emperor from AD 253 to 268), whose name, together with his wife Salonina's own, appears in the dedication above the archway.

This site corresponds to the ancient Porta Esquilina; the arch replaced the remains of the older gate, probably after the latter had become unused due to the making of the new wall by Aurelianus (271-275).
Here ran an important road, via Labicana, leading to Labici, and further south (see map of ROME'S ANCIENT SURROUNDINGS).

This is also popularly known as the arch of St.Vitus, from the name of the church that now supports this structure. On the right side of the church, along via Carlo Alberto, another small fragment of the Servian wall is easily identifiable, where its large blocks now bulge from a building, supported by bricks.

5. largo Giacomo Leopardi

A scarce trace of the wall can be found by the so-called Auditorium of Mecenas, the underground remains of a nymphaeum that belonged to the villa of the famous diplomat, who lived in the 1st century BC, now protected by a brick structure that covers the site. Originally, the wall ran across this spot, but when the villa was built the defensive structure had likely already fallen into disuse. Some of its surviving blocks now bulge from one side of the nymphaeum's modern cover.

NEARBY MAJOR FEATURES
basilica of Santa Maria Maggiore
Nero's Golden House

« via Equizia (Servian-like wall)

A 20 meter-long stretch of wall built with tufa blocks in opus quadratum style, very similar to others described in this page but completed with bricks, can be seen not far from spots 4 and 5 in the map.
It represents an interesting example of recycling of the useless remains of the republican wall during the imperial age. Above this structure stands the ancient church of St.Martin in Monti, founded in the 4th century and built on one of the steepest spots in Rome, the top of the Fagutal Hill (one of the three pikes of the Esquiline Hill), at the point that the making of a flat ground where to rest the building was required. The blocks it is made of undoubltly come from the Servian wall, but unlike the original opus quadratum, which followed the dry stone technique, these ones are kept together with a rough mortar, proving that they were arranged sometime later.

6. via di San Paolo della Croce

On a charming spot on the top of the Coelian hill stands a small ancient archway, whose inscription bears the names of two consuls, Dolabella and Silanus (AD 10): this is the site of one of the gates of the republican walls, Porta Caelimontana. Following the expansion of Rome's urban territory, the gate lost its original purpose, and was altered by the consuls into a simple archway.
When around the late 1st century AD a branch of a city aqueduct, named Arcus Caelimontani was built to provide the Coelian Hill with water (see Aqueducts, part III page 1), the tall duct crossed this spot, resting over the steady archway, where its remains are still seen today.

At the southern end of the area where the Circus Maximus stood is a wide avenue, viale delle Terme di Caracalla, leading to Rome's most famous ancient Baths.
At the beginning of the avenue, a stout square ruin lies in the grass on the eastern side of the road, opposite the site of the Axum obelisk: it is believed to be the remains of Porta Capena, the gate from which via Appia, also called regina viarum (queen of the roads) originally started. In fact, the present wide avenue corresponds to the first stretch of the ancient road; via Appia, though, now maintains its old name only beyond Porta San Sebastiano (see Aurelian's Walls, part III, page 2), that stands about 1.2 km - ¾ mile further south.

Since the ruin is not made of the usual large tufus blocks, but mainly of bricks, this may have been a fragment of a house, or another structure, built against the old wall once the latter had turned obsolete, rather than a part of the gate itself.

10. largo Magnanapoli

At the end of the valley between the Quirinal hill and the Viminal hill (corresponding to the long via Nazionale), just opposite to Trajan's Markets, in the middle of a traffic roundabout decorated with exotic trees is a small fragment of the wall, labelled as "remains of walls from the age of kings (i.e. the Servian wall) discovered in 1875".

But the most interesting feature, and the most hidden too, is housed in the hall of the historical building facing the roundabout, Palazzo Antonelli, at no.157, now a branch office of the Bank of Italy. Ask the porter to let you see "the roman arch": he will show you the way to what is believed to be the original Porta Sanqualis, which has been incorporated in the building's structure probably on the same spot where it originally stood: a very unusual architectural combination.
Other small ancient roman fragments are on display in the same hall, and in the adjacent courtyard.