Spandau Citadel

Listen first. Water moves quietly against old brick, and a duck lands somewhere in the moat. Under your feet the ground is firm and slightly uneven, packed earth and stone worn smooth by centuries of boots. Ahead of you, low red walls rise straight out of the water. They are not tall or showy. They are thick, angled and patient. This is Spandau Citadel, one of the best-preserved Renaissance fortresses in Europe. It sits at the edge of the old town, near where the Spree river meets the Havel.

Before we go inside, look at the shape of the place. From above, the citadel forms a square with a sharp, arrow-shaped bastion at each corner. This was the newest military idea of the sixteenth century. It came from Italy, where engineers had learned that round medieval towers could not survive cannon fire. Angled walls deflected cannonballs. They also let defenders fire along the face of the next wall, so no attacker could hide at its foot. Every line you see here was drawn for a reason.

The idea came with the people who built it. Work began in 1559, under the Electors of Brandenburg, the rulers of this region before Prussia became a kingdom. An Italian engineer, Francesco Chiaramella da Gandino, led the early construction. Another Italian-trained builder, Rochus Guerini, Count of Lynar, carried the project to completion in the 1590s. So the brick is local, but the plan is Italian. In a sense, you are standing inside an imported idea, built from the soil of Brandenburg.

The four bastions carry royal names: King, Queen, Crown Prince and Brandenburg. As you walk the ramparts, notice how the walls slope and turn. Small openings point along the outer faces, not straight out. Grass now covers the earthworks, and in summer the paths can feel almost like a park. But try to imagine the same space filled with powder smoke, shouting and the smell of horses. The calm you feel today is a fairly recent arrival.

Now here is the first surprise. The citadel is much younger than its oldest tower. Inside the walls stands the Julius Tower, a round, plain tower of stone and brick. It belonged to a medieval castle that stood on this island long before the Renaissance fortress. Parts of it date back to the twelfth or thirteenth century. That makes it one of the oldest surviving structures in all of Berlin. The Italian builders did not tear it down. They simply wrapped their new fortress around it.

The tower has a remarkable later story. After Prussia and its German allies defeated France in the war of 1870 and 1871, France paid huge reparations. A large reserve of gold coins from that money was sealed inside the Julius Tower as a war treasure for the new German Empire. It stayed there for decades, until the end of the First World War. The story became so well known that Germans still use the word Juliusturm for a government's hidden cash reserve. A whole political phrase comes from this quiet tower.

If the stairs are open, the climb to the top is worth it. From the crenellated crown of the tower, the geometry of the fortress becomes clear at last. You can see the star of the bastions, the dark ring of the moat and the rivers beyond. Church spires and rooftops of Spandau rise to one side. On a clear day, the wider sprawl of Berlin stretches toward the horizon. It is the best way to understand why this spot mattered.

Next to the tower stands the Palas, the old residential hall of the medieval castle. It is often described as the oldest secular building in Berlin, meaning a building not used for religion. And here is the second surprise. When the walls of this hall were studied, researchers found medieval Jewish gravestones built into them. They came from Spandau's old Jewish cemetery and had been reused as building stone. Today many of these stones are displayed with care, their Hebrew inscriptions visible again after centuries.

The citadel did not always live up to its strong design. In 1806, during the wars against Napoleon, French troops reached Spandau. The fortress surrendered without a serious fight. Later it served as a garrison, a prison and an arsenal. In the twentieth century the military used it for research, including work on gas warfare in the Nazi period. It is worth remembering that these handsome brick walls also carry darker chapters. A fortress is a tool, and it serves whoever holds it.

The present-day citadel carries a different purpose. Its buildings now house museums, studios and event spaces. One exhibition, called Unveiled, gathers political monuments that Berlin removed from its streets over more than a century. Emperors, generals and socialist figures stand together in one hall. The most striking piece is the huge granite head of a Lenin statue that once stood in East Berlin. It was buried in a forest after reunification, then dug up again to be shown here.

The citadel also has some unexpected residents. Its cool, damp cellars and vaults make an ideal winter home for bats. Thousands of them hibernate here each year, which makes it one of the largest bat winter quarters in Germany. Local conservationists run a bat cellar where visitors can learn about them and sometimes watch them up close. So while people walk the ramparts above, a quiet colony sleeps deep in the brick below. Few visitors expect wildlife in a fortress.

In the warmer months, the courtyard often changes character again. Open-air concerts and festivals fill the space between the old walls with music, food stalls and crowds. The same enclosure that was built to keep armies out now draws people in. One more note, because many visitors arrive confused. The famous Spandau Prison, where Nazi war criminals were held after the war, was a different site. It stood elsewhere in the district and was demolished. This citadel is not that prison.

Before you leave, stand still on the bridge for a moment. Look down at the water of the moat and the brick rising from it. Notice how the colour changes, from deep red to faded rose, where repairs meet older work. Listen again for the birds and the low sounds of the town beyond. Four and a half centuries of plans, wars and changes have passed through this gate. And now, for a little while, so have you.