Most visitors to Cologne see the cathedral and go home, and they miss the city's other great treasure. Long before the Gothic giant rose by the river, medieval Cologne built twelve great Romanesque churches, many of them over the graves of Roman-era martyrs, and they still ring the old center like a crown. This walk links five of them, from St. Kunibert near the Rhine to the bone-lined chamber of St. Ursula, the extraordinary domed St. Gereon, a corner tower of the Roman city wall and the clover-leaf choir of the Holy Apostles, and it ends at a museum of medieval art inside a Romanesque church. It is about three kilometers through quieter streets, and among our self-guided walking tours of Cologne it is the one for anyone who likes to slip away from the crowds.

Before you set off

The walking takes about forty-five minutes, but allow two or three hours so you can step inside the churches and spend time in the museum at the end. These are working parish churches, so they may be closed outside certain hours or during services, and the museum has its own times and admission, so check before you go. The route is flat and paved, but it crosses several busy roads, especially around Neumarkt, so use the crossings. Most of it runs through ordinary city streets rather than a postcard old town, which is part of the charm: you turn a corner past an office block and find a twelfth-century apse. Mornings are quietest. Bring a light jacket for the cool church interiors, a little cash for candles or the small leaflets some churches sell, and an umbrella, since Cologne gets plenty of rain. Dress respectfully and keep your voice down inside.

St. Kunibert

You begin a short walk back from the Rhine, at St. Kunibert, and the best place to stand is near the east end, where the rounded apse and its two slim towers rise above the street. This was the last of Cologne's twelve great Romanesque churches to be finished. It was consecrated in 1247, and only a year later work began on the Gothic cathedral just to the south, a building in a completely new style. So you are looking at the closing chapter of an age. The church is named for Kunibert, a bishop of Cologne in the seventh century, who is buried here. Step inside and walk up toward the choir. The stained glass windows in the apse date from the thirteenth century, among the oldest in Cologne still in the place they were made for, and when the morning sun comes through them the deep reds and blues glow like jewels. Local legend tells of a well beneath the church, and old Cologne folk told children that babies came from it rather than from the stork. Like all twelve of these churches, St. Kunibert was badly damaged in the bombing of the Second World War, and it was rebuilt with great care over the following decades. From here, head west, away from the river, passing under the railway lines that run north from the main station. In about nine minutes you reach a church whose tower is topped by a large crown.

Basilica of St. Ursula

St Gereon Cologne Look up at the tower and you will see a large crown on top, a nod to the princess this church is named for. According to legend, Ursula was a British princess who sailed with eleven thousand young women on a pilgrimage to Rome, and on the way home they were all killed by the Huns here at Cologne. The story grew over the centuries, and one popular theory is that the huge number came from a misreading of an old inscription that listed a far smaller group. What is real is a stone tablet set into the wall of the church, from late Roman times, recording that a man named Clematius rebuilt a basilica on the spot where holy virgins had died for their faith. In 1106, when the city extended its walls, workers dug into a large Roman burial ground here, and the bones they found were taken as relics of Ursula's companions. That is what makes the Golden Chamber, a side room fitted out in the seventeenth century, so startling. Its walls are covered with human bones arranged in patterns, zigzags and even letters, above rows of reliquary busts. If it is open, it is worth seeing. The story runs deep in the city. The eleven black flames on Cologne's coat of arms stand for Ursula and her companions. Now walk southwest for about eleven minutes, and look for a broad, many-sided domed church rising above the rooftops.

St. Gereon

Walk around to the west end and take in the shape of St. Gereon, unlike any other church in the city. Instead of a long nave there is a great ten-sided hall, the decagon, crowned with a ribbed dome. Its core is a late Roman building of the fourth century, an oval hall with niches that stood in a cemetery outside the city walls, where the dead had to be buried by Roman law. Tradition links it to Gereon, a Roman soldier said to have been martyred here with his companions for refusing to give up their Christian faith, and legend even credits the Empress Helena, mother of Constantine, with founding the first church. In the early thirteenth century the builders raised the old walls into the soaring decagon you see now, finished around 1227. It is often said to be the largest dome built in Europe between Hagia Sophia in Constantinople and the cathedral dome in Florence. Step inside if you can and stand in the middle. Look up into the ribs of the dome as they rise through tiers of windows, filled today with modern stained glass, and you feel the strange weight of a Roman room carried upward by medieval hands. From the church, walk south for about four minutes to the corner where Zeughausstrasse meets St.-Apern-Strasse, where a round stone tower stands at the edge of the pavement.