Nan Madol: The Basalt City of Pohnpei's Saudeleur Dynasty

Nan Madol is a ruined city built on nearly 100 artificial islets in a shallow lagoon off the island of Pohnpei, in the Federated States of Micronesia. From around 1180 to 1628, it was the seat of the Saudeleur dynasty, which ruled the whole of Pohnpei from palaces, temples and tombs made of massive basalt columns and coral rubble. It is one of the largest and most impressive ancient monuments in the Pacific, and in 2016 it was listed as a UNESCO World Heritage Site.

Background: Pohnpei before Nan Madol

Pohnpei is a high volcanic island in the eastern Caroline Islands of Micronesia. It was settled roughly 2,000 years ago by seafaring people whose ancestors probably came from island Melanesia to the south, part of the wider story of Pacific voyaging that also produced the settlement of East Polynesia.

For centuries, the island was divided among smaller chiefdoms. Archaeological evidence shows that people were using the reef flat at Nan Madol by the late first millennium AD, perhaps first for fishing and small shrines. The great stone architecture came later.

Pohnpei’s rich volcanic soils and heavy rainfall supported breadfruit, yams, taro and bananas, while the surrounding reef and lagoon provided abundant fish and shellfish. This productive environment helped make it possible for an island of only about 340 square kilometres to support a ruling elite, priests and the large labour force needed for monumental building.

Building the islets

Nan Madol covers an area of about 1.5 kilometres by 0.5 kilometres along the coast of Temwen Island. Its name is usually translated as “spaces between”, referring to the network of tidal canals that separate the islets, which has led to its nickname “the Venice of the Pacific”.

Each islet was built by laying long basalt columns, which form naturally as volcanic rock cools, in alternating crosswise layers, much like a log cabin. The spaces inside were filled with coral rubble to create raised platforms. Some walls reach about 7.6 metres (25 feet) high. Scholars have estimated the total weight of stone at about 750,000 metric tonnes, though such figures are approximate.

A 2016 study using uranium-thorium dating of coral from the site found that the main royal tomb on the islet of Nandauwas was built around 1180 to 1200. This is the earliest securely dated monumental tomb in Pacific Oceania. Construction continued in phases over the following centuries.

How the stones, some weighing several tonnes, were moved remains uncertain. Geochemical studies suggest they came from more than one quarry on Pohnpei. They were probably floated on rafts along the coast and raised with ramps, ropes and levers. Pohnpeian legend says they flew into place through the magic of the founders.

The Saudeleur dynasty

According to Pohnpeian oral tradition, two brothers, Olisihpa and Olosohpa, came by canoe from a land to the west and sought a place to build an altar to the god of agriculture. After several attempts, they chose the reef off Temwen. When Olisihpa died, Olosohpa became the first Saudeleur, meaning roughly “lord of Deleur”, and ruled all of Pohnpei.

The Saudeleurs created the first centralised government on the island. Traditions describe them as increasingly demanding, requiring heavy tribute in food and goods and controlling the religious life of the island. Nan Madol was the stage for this power.

Bringing the island’s chiefs and their families to live at or near the capital helped the Saudeleurs keep watch over potential rivals. Food for the elite who lived on the islets, where little could be grown, had to be brought in by canoe from the main island. Tradition also describes a sacred eel kept in a pool on one of the islets, which was fed with turtle offerings and played a part in the religious life of the court.

The complex was divided into two parts. Madol Pah, the lower town in the southwest, held the ruler’s residence and administrative and ceremonial buildings. Madol Powe, in the northeast, was the mortuary area, with priestly residences and tombs. Its largest structure, Nandauwas, has high double walls around a central burial chamber, where tradition says the Saudeleurs were buried.

The fall of the Saudeleurs

Tradition holds that the last Saudeleur, Saudemwohl, was overthrown by Isokelekel, a half-divine hero from the island of Kosrae, about 550 kilometres to the east. He is said to have arrived with a band of warriors, sometimes numbered at 333, and won a decisive battle after a long conflict. The overthrow is commonly dated to around 1628, a date derived from genealogies and archaeological estimates rather than written records.

Isokelekel established a new political order, the Nahnmwarki system of paramount chiefs, which still survives in ceremonial form on Pohnpei today. Nan Madol lost its role as the island’s capital, though some islets continued to be used for rituals and burials. By the 19th century, when Europeans began to visit, the site was largely abandoned and overgrown.

In the late 19th and early 20th centuries, European visitors and officials, including German administrators after Germany acquired the Caroline Islands in 1899, dug into some of the tombs. Systematic archaeological research began only after the Second World War, and studies since the 1960s have mapped the islets, dated the construction phases and traced the sources of the basalt.

Myths and facts

• Myth: Nan Madol is the remnant of the lost continent of Mu. The writer James Churchward popularised this idea in the 1920s. There is no geological or archaeological evidence for any sunken continent in the Pacific.
• Myth: It is impossibly old or built by outsiders. Dating and oral traditions alike show that Nan Madol was built by Pohnpeians, mainly from the late 12th century onwards.
• Fact: Nan Madol was not a “lost” city. Pohnpeians have always known of it, and its story is preserved in their oral traditions.

Preservation

In 1985 Nan Madol was declared a National Historic Landmark of the United States, which then administered the region as part of the Trust Territory of the Pacific Islands. In 2016 it became the first UNESCO World Heritage Site in the Federated States of Micronesia. At the same time, it was placed on the List of World Heritage in Danger, because silting of the canals and the spread of mangroves are damaging the walls.

Comparable achievements in Pacific monument-building include the moai of Rapa Nui, though the two cultures developed independently.

Timeline

• c. 2,000 years ago: First settlement of Pohnpei.
• Late 1st millennium AD: Early use of the reef flat at Nan Madol.
• c. 1180–1200: The royal tomb on Nandauwas is built, according to coral dating.
• c. 1200–1600: Saudeleur rulers govern Pohnpei from Nan Madol; construction continues.
• c. 1628: Isokelekel overthrows the last Saudeleur, according to tradition.
• 1985: Nan Madol is declared a US National Historic Landmark.
• 2016: Inscribed on the UNESCO World Heritage List and the List of World Heritage in Danger.

Why it matters

Nan Madol shows that a small Pacific island could support a centralised state capable of monumental building on a scale rarely matched in Oceania. Its basalt walls, tombs and canals record the rise and fall of the Saudeleur dynasty and the political traditions that still shape Pohnpei. It is a reminder that the Pacific had its own medieval kingdoms, built by islanders with their own skill and vision.