Most visitors look on Cologne’s cathedral as a mighty medieval marvel. It’s not.

In fact, much of the city’s Dom St Peter, or Kölner Dom, is comparatively new among Europe’s great cathedrals. Its completion was the culmination of a complicated process and a chance discovery.

The result is a magnificent cathedral, one of the world’s biggest churches with a vast interior space that make it No.5 in the world by volume. Its extraordinary scope alone would make it worth the visit.

The towers are 157m high and the building is 144m long. The internal height of the nave vault is 43m. The biggest bell weighs 24 tonnes.

It is said the building, covering almost 8,000 sq m of usable space, could accommodate 20,000 people, although the roofed area is more than 12,000 sq m. By enclosed area, it is No.18. Its size means that renovation work is constant.

The cathedral where kings did homage

Cologne played an important role in medieval Germany, having close ties to the German throne. Ecclesiastical power was established early and by medieval times Cologne’s prince-archbishops were power brokers in the Holy Roman or German empire.

The archbishop of Cologne anointed medieval Holy Roman emperors in Aachen before they were crowned German king, one of their titles. A ritual procession then took place from Aachen, through Cologne’s western gate the Hahnentorburg, to the cathedral.

From 1164 the monarch did homage before holy relics of the Three Magi as part of a procession and an elaborate coronation protocol. The associated rituals added to Cologne's mystique and power as a holy city, protecting many churches and abbeys.

The Cologne archbishops were also key political players with a powerful voice in naming each new emperor. Three crowns, representing the Three Magi, were part of the city’s heraldic arms.

If you want to piece together the cathedral’s history, look down. The parts of the vast mosaic floor in the ambulatory show images of the Cologne archbishops and bishops, their churches, and their heraldry.

Medieval ideas wait for a modern cathedral

The big problem facing the historical builders was how to build the cathedral.

We cannot quite call today's building medieval, though the concept belongs to Cologne’s medieval period. Though largely recent work, it was completed after the rediscovery of medieval plans and reflects those closely.

In truth, the cathedral is Gothic and Neogothic, but the blend is a success. According to UNESCO, "no other cathedral is so perfectly conceived, so uniformly and uncompromisingly executed in all its parts".

The building project, started in 1248, was not complete until the 19th century, having come to a stop in 1473. Work restarted, then halted again in 1560. The cathedral remained unfinished for centuries. Generations came and went, knowing its crane as the most prominent element of Cologne’s skyline.

The chief problem was lack of funds. Though a rich Rhine trading port in Roman and medieval times, the city of Cologne went through an economic depression after the Thirty Years War and coastal ports of north-western Europe attracted most of the growth through Atlantic trade. Cologne’s population remained static.

Work on the cathedral had to wait. Under French troops who entered Cologne in 1794, the building was used for storing grain and housing prisoners.

After this there were repairs, but building did not resume until 1842, when industrialisation was getting the economy moving.

About 600 years after work on the cathedral began, the rediscovery of 13th century plans for the cathedral facade was a breakthrough. A spirit of Romanticism was growing, stimulated by medievalism.

Germany’s new Prussian rulers, although Protestant, took their opportunity to win over the Catholic majority of Cologne citizens by funding half the completion cost so builders could get back to work. The Prussian regime was keen to connect itself with Germany’s medieval imperial greatness by delivering a prestige project and a new symbol for the city with a Prussian stamp.

A magnificent new window, depicting the Adoration of the Magi, was added to the cathedral’s treasures. A group of Cologne citizens produced much of the rest and in 1865 started a lottery to raise further cash to build the mighty towers.

In 1880, the south tower topped out at last. For four years, the cathedral was the world’s tallest building, and was surpassed as the tallest church by only 4m in the single tower of Ulm Münster in 1890.

Cologne’s forever church

Kölner Dom followed a tradition of church building on the site going back more than 1300 years.

The city had a bishop from Cologne’s Roman period early in the 4th century and its first Christians worshipped in a private house that probably stood on the cathedral site. There was also a baptistery. A proper episcopal church up to 50m long followed in the 6th century.

A Romanesque cathedral almost 100m long – vast for its time – followed late in the 9th century. An atrium with arcaded courtyard, almost as long, was attached. Cologne had already become a power centre for the medieval church.

Change came in 1164 when the relics of the Three Magi, the bequest of the emperor Frederick Barbarossa, were brought from Milan to Cologne. Cologne already had a reliquary staff and links of a chain attributed to St Peter. The new attraction made Cologne a key European pilgrimage centre.

The arrival of the new shrine for the relics 60 years later made a bigger, wider cathedral necessary to accommodate crowds. When building of the Gothic design started, haste in demolishing part of the old cathedral caused damage that had to be made good and part of the Romanesque building had to be temporarily reconstructed. A fire caused further delays.

Medieval masterpieces of church art

What is medieval in Cologne cathedral is the choir, with 14th century windows regarded as Europe's biggest of the period. The black marble high altar and the stalls come from the same period.

But the cathedral’s greatest medieval treasure is the precious Shrine of the Three Magi or Dreikönigsschrein, completed in 1225, a shining example of the art of the Low Countries that took more than three decades to produce.

The goldsmith Nicholas of Verdun and other craftsmen produced the glittering shrine of silver and gold plate, studded with precious gems, combined of three elements and shaped like a Romanesque church.

Figures on the shrine show figures of the Magi, the life of Christ and the prophets of the church. It long stood in the cathedral crossing but was later moved to the rear of the choir, behind the high altar.

Other precious medieval objects include a Cologne-made altarpiece showing the Adoration of the Magi, the Cologne patron saints St Ursula and St Gereon, a work by Stefan Lochner from the 1440s. It brings together the city’s patron saints.

A nearby pillar sculpture known as the Madonna of Milan, actually carved in Cologne, comes from about 1280. Its name comes from the original, said to have arrived from Milan with the Magi relics, which it replaced after a late 13th century fire.

A carving of St Christopher bearing Christ, from about 1470, is almost 4m high.

Also among the altarpieces is the St Agilulf altar, a Flemish work from the early 16th century that depicts Christ’s Passion, as well as the saint-bishops Agilulf and Anno.

The so-called Gero Crucifix, in oak and believed to have been carved about 970, is associated with an archbishop of the period. It is 3m high and the earliest of its type north of the Alps, although the surround is later Baroque work.

The staff of St Peter is on display in the Dom museum, along with other treasures that require books of description.

Cologne’s
cathedral today

The towers are visible for many miles and visitors hoping to climb the south-west tower face a trudge of more than 500 steps in a narrow space to get almost 100m up to the viewing platform.

This mighty church was also the scene of a miracle – its survival in the face of World War II bombing. More than three years after heavy Allied air raids on Cologne began, its towers stood among the debris of the city with surprisingly little damage, apart from the loss of part of the transept roof and damage to walls. Pock-marked stones still show impressions of the last struggle for the city, including a tank battle.

Estimates are that 95% of the city was destroyed, but Cologne’s cathedral remained standing above the battle.

When photographed, the cathedral, blackened and grey from centuries of city smoke, often takes on a gilt appearance, especially when the sun is low in the western sky.

Visiting Cologne’s cathedral

Kölner Dom is only a few minutes’ walk from the city’s main station. There are up to six masses daily, which can close the church to visitors. Public tours are available.

Let Raven Travel Guides Europe be your go-to resource for affordable and unforgettable European travel experiences. Check out the Cologne city guide, the blog on its second-biggest church, Great St Martin, or explore more Germany travel tips.