One man crossed the world. You walk its final stretch.

The group, having left Barcelona on a Spanish ship and called at Saint-Tropez, Savona and Genoa, this time on a Genoese ship, entered the port of Civitavecchia through the eastern mouth after four days at sea.

From the deck the delegation, which included the friars, the interpreter Scipione Amati, author of the embassy’s chronicle, and Hasekura himself, took in the fortified town at a glance: the bell towers, the Rocca with its crenellated tower taller than any other building, the Fort with its keep and its corner towers with conical roofs and, right at the entrance, the lantern of the new lighthouse, still wrapped in scaffolding, erected by Paul V Borghese, the pope they were travelling to meet.

The anchor was dropped in the main basin. Amati went ashore in a felucca to present himself to Governor Severolo and announce the ambassadors’ arrival, and Hasekura and Sotelo were then lodged in the Rocca, where they found shelter and rest; that same evening they wrote to the pope’s nephew, the all-powerful Cardinal Scipione, asking permission to travel on to Rome.

The arrival took place on 20 October 1615, according to the most recent studies of Amati’s chronicle; by tradition, however, it had been celebrated on the 18th, from the twinning of 1971 to the four-hundredth anniversary in 2015. On 24 October the delegation left the town and took the road south.

To leave Civitavecchia the procession went through Porta Romana, leaving behind the new bastioned defences that Paul V had commissioned from the architect Pierpaolo Floriani of Macerata. On the right lay the Tyrrhenian Sea with its small bays; on the left, in the distance below the inland hills, the small tower of the Palazzaccio; shortly afterwards came the Marangone tower, now almost invisible among the port buildings and the village of the Repubblica dei Ragazzi.

All around were Mediterranean scrub, a few vineyards and wheat fields, among them the lands of the Franciscans, the estate of the Fosso del Lauro, popularly known as a fabulous “Field of Gold”, a place of hidden treasures. Today that stretch is an urbanised strip leading to Riva di Traiano.

Civitavecchia was born as Centumcellae, the port Trajan had built at the beginning of the 2nd century in front of his seaside villa. The National Archaeological Museum, housed in an 18th-century building near the port, tells the story of Centumcellae, the coastal villas and the Taurine Baths, and devotes a section to Leopoli-Cencelle, the medieval town founded in 854 by order of Leo IV.

Forte Michelangelo, commissioned by Julius II to defend the port from pirates, had its foundation stone laid on 14 December 1508 to a design by Bramante; it was continued by Antonio da Sangallo the Younger and completed in 1537 under Paul III, and dedicated to the Archangel Michael. Its name has linked it to Michelangelo Buonarroti, but this is a local tradition with no supporting evidence. Little remains of the town Hasekura saw, because the war erased much of its historic centre; but the port, the Fort and the Rocca are still there to recall that scene.

The twinning with Ishinomaki, the Japanese city from which the mission set out, established in 1971, can be seen in several places around the town. In front of the statue of Hasekura, with the story of the journey told on the marble plaques and the map that surround it, you understand why this is the most symbolic starting point.

Not far away, in the garden known as the “Pincio”, next to the Town Hall and the Council Chamber, a large engraved boulder with texts in two languages is the last trace of the Japanese garden that Ishinomaki gave the town on the occasion of the twinning.

The Way then passes in front of the Church of Saints Peter Baptist and Companions, Japanese Martyrs. Its history is inseparable from that of the mission: in 1597, in Nagasaki, twenty-six Christians, six Spanish missionaries and twenty Japanese, were crucified on the orders of the regent Toyotomi Hideyoshi; this began the process that led to their canonisation, completed on 8 June 1862. The church was consecrated on 13 June 1872 with the offerings collected for the canonisation cause; destroyed by the bombing of 30 August 1943, it was rebuilt and reconsecrated on 4 October 1950.

The walls were still bare when the Japanese painter Lucas Ryuzo Hasegawa (1897-1967), a convert to Catholicism who had come to Rome for the Holy Year, received from Japan’s representative to the Holy See, Agostino Kanayama, the proposal to fresco them. He worked on the church from 1951 to 1957; the apse was inaugurated on 10 October 1954. It shows the famous Madonna in a kimono with the Child, the scene of the twenty-six martyrs crucified in Nagasaki on 5 February 1597, Saint Francis Xavier and Saint Francis of Assisi and, at the sides, Saint Fermina, the town’s patron saint, and Hasekura Tsunenaga himself.

The next morning the group set off again along the Aurelia and crossed the Perazzeto and Sassettara streams on ancient bridges, while Monte Sassone stood out on the left. One after another came the Cento Corvi farmhouse (now Casal Turbino), the Sasso estate of the Patrizi marquises with its granary, that of the Salviati family with Montetosto and the Zambra stream; far off, against the sea, perhaps Torre Flavia could be glimpsed.

Inland you could make out the towered walls and the castle of Cervetre, another medieval name for the place; then came the inn of Vaccina. It was a landscape where a few buildings dotted wide open spaces: farmhouses, post inns and towers along the coast.

Cerveteri is ancient Caere, one of the richest Etruscan cities, which from the 7th century BC dominated trade in the Tyrrhenian Sea and controlled, through the ports of Pyrgi and Alsium, the coast we are walking. It was a city of learning: ancient sources record that the Romans sent their children there to receive a cultural and artistic education, before the city’s rebellion against Rome in 273 BC led to the loss of part of its coastal territory, where the colony of Fregenae was founded. Walking along this coast you are walking, in a sense, through the maritime territory of Caere.

In Hasekura’s time the coast between Santa Severa and Ladispoli was largely an expanse of marshland, glimpsed from the Aurelia towards the sea with the outline of Torre Flavia in the background. Land reclamation has erased that landscape; a protected fragment of it remains, the Torre Flavia Marsh Natural Monument, on the northern outskirts of Ladispoli and on the border with Cerveteri, a refuge for migratory birds.

The sixteenth-century tower, restored by Cardinal Flavio Orsini, is now a ruin partly eaten away by the sea: today’s Way, which follows the new route, passes right beside it, whereas the party of 1615 on the Aurelia only glimpsed it from afar.

Further north, between Santa Severa and Marina di Cerveteri, just over a kilometre from the route, lies another large oasis, the Macchiatonda Nature Reserve, a wetland with ponds, rush beds and a small laurel wood, crossed by the network of nature trails of the Strada dell’Idrovora and the Strada dei Capanni.

At Palidoro the party stopped for lunch. The Aurelia passed beside the massive Palidoro tower, while a little further on rose the square towers of the castle of Statua, which collapsed in 1944; the Cupino stream was crossed on a single-span travertine bridge, from which a large circular tomb could be seen.

Then they entered the village, with the church of Saints Philip and James. Palidoro, the Curtis Palidori, passed in 1360 to the Hospital of Santo Spirito, which kept the whole estate. The lunch was, as almost everywhere on the journey, rich and generous: the abundance of the welcome is one of the threads running through the embassy’s chronicle.

The historical route continued to Torrimpietra, where they admired Palazzo Falconieri with its fountain and the Pagliaccetto tower, then to Maccarese, with its village dominated by the medieval castle of San Giorgio, later owned by the Rospigliosi.

Here, as north of Civitavecchia and in the Agro Pontino, the land was marked by uncultivated, unhealthy marshes running parallel to the sea behind the beach and the dunes. The pine forest we still see today dates back to 1666, when it was planted by Clement IX; Fregene was then a fishing village.

Further on they crossed the Arrone, the outflow of Lake Bracciano, and passed the fourteenth-century Bottaccia farmhouse, to reach the post station of Castel di Guido, ancient Lorium, where the emperor Antoninus Pius had died in AD 161.

At Palidoro the coastal tower known as Torre Perla stands on an earlier Roman seaside villa and overlooks a farming landscape within the Litorale Romano State Nature Reserve.

On 23 September 1943, near this tower, the Carabinieri vice-sergeant Salvo D’Acquisto was killed after saving twenty-two innocent people by offering his own life in their place; a marble stele has commemorated him since 1960. Behind it stretch the dunes, a refuge for birds such as the Kentish plover and for rare plants such as the sea daffodil, which the Way follows for a stretch along the beach.

To the south, Maccarese and Fregene tell a story of water and work. Maccarese, long owned by great Roman families, was reclaimed from 1925 onwards and settled by farmers from Veneto and from Mantua.

Fregene, on the site of the ancient Roman maritime colony of Fregenae, founded around the middle of the 3rd century BC on land taken from Caere, was reborn in the twentieth century as a seaside resort, as part of the great land reclamation works along the coast.

The Way passes a short distance from the Palidoro tower, runs along the Passoscuro dunes, crosses the village, skirts Fregene along the pine forest and the cycle path, passing not far from the Maccarese coastal tower, then reaches Fiumicino and turns towards Parco Leonardo, the modern district around the station that marks the transition from countryside to city. The castle of San Giorgio and the reclaimed countryside of Maccarese remain inland.