Battle lines: creating a memorial to a battle of mythical importance with no obvious surface traces necessitated architectural imagination of great sensitivity which has overlaid past with present, place with narrative, time with space.

The battle of the Teutoburger Wald changed the world. In AD 9, the Roman general Publius Quintilius Varus lost three legions and six supporting regiments of auxiliaries. He had marched over the Rhine and into the German forest to try to bring local tribes, including the Cherusci, under Roman influence, but very few of the 25 000 men of his army escaped and he fell on his sword on the battlefield. A combination of arrogant disdain for the Germans (whom he thought savages) (1) and bad tactics had allowed him to be surprised by a powerful army of Cheruscan javelin throwers who emerged from the apparently trackless forest and retreated again, only to launch another surprise attack, and another, and...

The Romans could not retreat because of a marsh, and according to Tacitus, (2) their last remnants died in heaps on the ramparts of their immaculately ordered rectilinear camp. Arminius, the Cheruscan general, was no barbarian, he could speak Latin and had served Rome as an auxiliary officer. But he had invented a new way of fighting that combined traditional forest tactics with a version of Roman discipline, which served to keep the empire at bay. (3) After the battle, the emperor Augustus abandoned the dream of extending the imperial border to the Elbe, and for centuries his successors established the Rhine as the effective edge of Roman territory in Germany.

Some 20 hectares of forest and farmland at Kalkriese near Osnabruck in northern Germany has been determined by archaeologists to be the long-lost site of the battle. Annette Gigon and Mike Guyer won the competition to create an archaeological museum and park, and they have approached the task with poetic insight, gentleness and (because of a restricted budget) thoughtful economy.

Far from having the precise geometry of the Roman camp as described by Tacitus, the site (4) reveals a long sinuous earthwork constructed by the Cherusci at the edge of what was then probably a dense oak and beech forest. Gigon & Guyer describe the course of the rampart with a long curving row of vertical steel tubes, close together where archaeology has shown the exact route, further apart where evidence is more sketchy. The Roman line is described by a roughly parallel curve of flat steel plates laid irregularly to describe the places where the legions fell. Behind the poles to the south, the forest is being densely replanted to show the probable edge from which the troops of Arminius attacked. Into existing and new woodland is cut a network of narrow wood-chip covered paths, intended to suggest the routes by which the Cherusci advanced and retreated. To the north of the lines, there is no effort to recreate ancient landscape on a large scale. Here, field edges of recent agriculture have been preserved as g ravel paths through grassy parkland. So three patterns are woven together: the modern agricultural scale, the dense woodland network and the battle lines in between.

A long, broad rectangular excavation, running roughly north to south, is intended to show the lie and nature of the original terrain. At its south end, it touches the woods. The German rampart is topped by a wattle fence and the Roman side gradually changes from sandy soil to the start of the marsh described by Tacitus. (5) Round the generous trench is a border of sheet steel piling which acts both as a means of defining the excavation and a railing. The route of steel plates defining the Roman line comes to one edge of the excavation and you are led round it by a double row of steel piles that encloses the path before it takes up its sinuous route again.

Steel is an appropriate material for the park structures for several reasons. For over two millennia, iron (or steel) has been the principal metal of war, and it was with iron weapons that the Romans and Germans fought each other. Steel is cheap: the plates laid on the Roman line are those commonly used to cover temporary holes in streets during repair works; the hollow poles are similar to scaffolding elements found on any building site, but ungalvanized; the sheet piling is standard. Most of these elements have been given a rusted finish, which adds to the haunting melancholy of the place as it slowly stains the surrounding earth.

A new museum building in the south-west corner of the site enhances the experience of the park. (6) It takes advantage of the sloping site to allow entry under the main bulk of the building. The museum itself is fundamentally a long single-storey exhibition gallery, lit partly by large screenable glass windows. To the north of the block, a tower rises to provide a viewing platform that overlooks the whole site. Built, like the gallery, with a steel frame covered in large, storey-high rusted steel panels, the tower's cladding is cut back irregularly to frame particular views as you go up. From a distance, over the trees, this high part of the museum has a rather sinister resemblance to twentieth-century military watchtowers.

Scattered over the meadowland are three small pavilions, made, like the museum, with rusted steel plates over steel frames. Like the museum, they have a vaguely menacing, melancholy air. They are devoted to seeing, listening and understanding. (7) The seeing pavilion, the first you come to, has a camera obscura lens bulging eye-like out of its front. Inside the little chamber, the device provides a disconcerting inverted fish-eye view of the park. The hearing pavilion has a huge, movable, galvanized steel ear-trumpet on top, evoking vague memories of First World War listening devices. In the understanding pavilion at the end of the winding path, television clips of contemporary conflicts are shown on nine screens; slits offer views over the meadow where so many died so long ago. Externally, this pavilion has disturbing overtones of abandoned blockhouses or military vehicles.

The vague menace of the buildings is never overdone but, by generating almost subliminal echoes of the wars of the twentieth century, the violence and horror of the site are evoked in a way that could not be achieved with factual displays alone. All the buildings touch the ground lightly; the plates of the path and the poles can be removed, so continuing archaeological studies will not be impeded. The site will change over time: trees will grow; new pavilions will be built; the buildings will weather and weep rust the colour of old blood; maybe the remains of the Roman camp will be found. Gradually, the place will deepen our understanding of the battle between the armies of Varus and Arminius, what it meant to its participants, and what it means to us today.

(1.) Schama, Simon in Landscape and Memory, Harper Collins, London, elegantly summarizes Tacitus's account and contemporary records (and later interpretations of the event).

(2.) Who wrote his Annols of Imperial Rome about a hundred years after the battle, but drew on now lost contemporary sources.

(3.) Though Tiberius's nephew, Germanicus led a punitive mission into Germany six years after the battle, it had no lasting effect. He made a funerary mound of the remains of the Romans of the Teutoburger site, and retreated back over the Rhine after brutal massacres and ultimately indecisive battles.

(4.) Landscape architects were Zulauf/Seippel/Schweingruber.

(5.) The swamp has been drained for agricultural use, and is generally replaced by pasture.

(6.) The existing farm buildings have been retained, and act us entrance to the whole plate and visitor centre.

(7.) The exhibitions of the museum and the pavilions were organized in collaboration with integral Concept.