The Hidden Story of the City’s Defences

Lisbon is often described as a city built on seven hills. But long before those hills became viewpoints, streets and neighbourhoods, they were part of something else: a defensive landscape.

For almost two thousand years, Lisbon repeatedly changed the shape of its walls.

Some were built by the Romans. Others were created or transformed under Muslim rule. And in the fourteenth century, as the medieval city expanded far beyond its older limits, a much larger defensive circuit was built under King Fernando I.

Today, the walls have almost disappeared from the landscape.

But they have not disappeared completely.

They survive in unexpected places: behind modern buildings, inside hotels and shops, between houses, along narrow streets and even in the shape of the city itself.

And once you start looking for them, Lisbon begins to tell a different story.

The first wall: a Roman Lisbon

The oldest wall in this story dates from the final centuries of the Roman Empire.

This was a very different Lisbon from the one we know today. The city was still known as Olisipo, and its position on the Tagus made it an important urban centre on the western edge of the Roman world.

By the late 4th or early 5th century, the city needed stronger defences. A substantial new wall was built around the urban core, incorporating or replacing earlier defensive structures.

A fragment of this wall survives today inside the Áurea Museum Hotel.

It is an extraordinary place to encounter ancient Lisbon: not in an archaeological park or an isolated monument, but inside a modern building, where the wall has simply remained part of the city.

Almost seventeen centuries later, Lisbon is still built around it.

The Moorish wall: a city behind its walls

The Roman wall did not disappear when Muslim rule came to Lisbon.

After the conquest of the city in the eighth century, its defensive system was adapted, repaired and extended. Over the following centuries, Lisbon developed as al-Ushbuna, a Muslim city whose fortified core occupied the hill above the Tagus.

This is what is usually called the Moorish Wall, or Cerca Moura.

The walls were not simply a barrier separating Lisbon from the outside world.

They shaped the city within.

The narrow streets of Alfama, the steep slopes and the surprising changes in level are partly the legacy of a city that developed inside and around fortified boundaries.

And the walls were not always destroyed and rebuilt from scratch. Later builders often incorporated what was already there.

That is why Lisbon’s defensive history is not a simple sequence of three separate walls.

It is a story of layers.

Here the layers become almost tangible.

At the bottom are the remains of the Roman defensive system. Above them, the later construction of the Moorish period incorporated and adapted what was already there.

A city does not always erase its past. Sometimes it builds on top of it.

Gates, wickets and the medieval city

A fortified city needed more than walls. It needed entrances.

The Moorish walls had large gates through which people, animals and vehicles could pass, but they also had much smaller openings intended for pedestrians. These small entrances are known in English as wickets or postern gates.

One survives in Alfama.

These small openings could have a surprisingly lasting effect on the city.

In southern Alfama, some of the old entrances through the walls became passageways and stairways connecting the lower part of the city with the neighbourhood above.

What began as a defensive necessity eventually became part of Lisbon’s urban fabric.

The wall disappeared but the passage remained.

The wall that made Lisbon bigger

By the fourteenth century, Lisbon had outgrown its older fortifications.

The city had expanded far beyond the limits of the old medieval core, and the political situation made new defences increasingly urgent.

Between 1373 and 1375, during the reign of King Fernando I, Lisbon acquired a much larger defensive circuit: the Cerca Fernandina.

It enclosed more than six times the area enclosed by the older Cerca Moura — and stretched for roughly 5.4 kilometres.

The new wall changed the geography of Lisbon.

It crossed areas that today seem completely unrelated to a medieval fortress.

One of them is Martim Moniz.

Look up from Martim Moniz towards Mouraria and the topography begins to reveal the logic of the old defences.

The wall crossed the valley and then climbed the hillside, eventually connecting with older fortified structures around the upper part of the city.

The modern city has grown around it, but the hills still remember where the wall went.

When the wall becomes almost invisible

Some sections of the Cerca Fernandina are surprisingly difficult to find.

Others are hiding in plain sight.

Inside a modern shopping centre near the former Porta de Santa Catarina, an enormous fragment of the fourteenth-century wall survives behind glass.

The surroundings could hardly be more different from those of medieval Lisbon.

Shops, escalators and modern architecture have replaced the houses and streets that once stood here.

Yet the wall remains.

It is a reminder that Lisbon’s history is not always found in monuments deliberately preserved as monuments.

Sometimes it is simply what refused to disappear.

The former Porta de Santa Catarina was one of the important entrances in the western section of the Cerca Fernandina, built between 1373 and 1375.

Three walls, one Lisbon

A Roman wall, a Moorish wall and a Fernandine wall.

Three defensive systems, built in different centuries, by different rulers, for different reasons, but they belong to the same city.

And, remarkably, parts of all three can still be found today.

They can be monumental, almost invisible, or even buried beneath modern buildings.

Sometimes they have become a shopping-centre feature in Chiado, a hotel interior or a staircase in Alfama.

That is what makes Lisbon’s walls so interesting: they are not simply ruins.

They are layers of the city.

And once you learn to see them, Lisbon itself becomes a kind of archaeological map — one in which Roman, Muslim and medieval Lisbon are still quietly present beneath the modern city.

**Three walls.

One Lisbon.**