To find the beginnings of Bremen, go to its cathedral. The site of St Petri Dom has been the focus of more than 1,200 years of worship. Churches have been built and rebuilt within its foundations since 789, when the missionary and first Bremen bishop Willehad had a wooden church set up.

St Petri Dom today preserves much of Bremen’s earliest history. But it is more than that – it was the base from which missionaries brought the word of God to Bremen and much of northern Europe was Christianised. But the cathedral also tells a story of dispute and conflict within Christianity.

Willehad’s first church was destroyed by a Saxon attack early in the 790s. About 805 a stone church replaced it and St Ansgar consecrated a pre-Romanesque hall church about 860.

In 1041 a fire in Bremen destroyed this building and reconstruction in sandstone began immediately, apparently inspired by the contemporary cathedrals in Cologne and Benevento.

Medieval cathedral stands strong today

The three-aisled, Romanesque flat-roofed basilica had two crypts that still exist, preserving (especially in the east crypt) their 11th century Romanesque features, although the west crypt is considered older. Eight bodies mummified by the basement environment were discovered about 1698 and these are displayed in the lead cellar off the courtyard, open to visitors from April to October.

Also in the crypt is a 13th century bronze baptismal font is supported by figures riding lions and almost 40 figures including Jesus, angels and the apostles. There are capitals with what look like pagan images and more than 80 graves of early bishops and church identities remain.

Also surviving from this period is the cathedral mouse near the foot of the south portal of the east choir, added by a stonemason and usually taken as a symbol of the dangers of witchery and devilry and an attempt to banish both from the building.

A city seal from about 1230 shows there was a rose window. The west towers were extended and vaulting was built from 1250. Most of this work used bricks, partly faced in sandstone. Gothic side-chapels were added in the 14th century and there were further extensions early in the 16th century that provided a net vault.

Despite additions, repairs and restorations, the Dom St Peter retains the overall look of a medieval cathedral today.

Bremen’s influence extends across the north

Charlemagne had converted the Saxons of the Weser region from paganism by fire and sword. But when Bremen’s turn came to spread Christianity further through Denmark and Sweden, it used the missionary approach. For almost three centuries the combined archdiocese of Hamburg-Bremen included much of Scandinavia.

The missionary St Ansgar travelled deep into Sweden in 829, staying six months at Birka near modern Stockholm. In 845, as newly appointed archbishop, he moved his seat to Bremen, visited Denmark and Sweden and in 853 he returned to Birka, establishing churches as he went.

Ansgar’s efforts failed to establish permanent worship but he has gone down in history as the ‘Apostle of the North’. His successor St Rimbert returned to Scandinavia to continue the work. By the 12th century there were 20 Scandinavian bishoprics under Bremen’s authority.

Bremen’s maritime strength and influence was for centuries an advantage in its northern missionary work.

The north of Europe remained part of Bremen’s church region until Christianity was fully established and Lund, then part of Denmark, became an independent archbishopric in 1104.

Cathedral in dispute

The Reformation both disrupted and interrupted the cathedral’s history and the building had mixed denominational uses for centuries.

Lutheran pastors preached alongside Catholic priests from 1522 until 1532, when the Catholic archbishop Christoph von Braunschweig-Wolfenbüttel closed the cathedral. It reopened with a Lutheran pastor in 1547, only to close again in 1561 for more than 70 years over Protestant doctrinal disputes. But the bishopric remained Lutheran in the decades leading up to the Thirty Years War.

In the 1590s Bremen’s citizens officially adopted Calvinism in place of Lutheran beliefs, but when the cathedral reopened in 1638 Lutheran doctrines were still being preached.

But the cathedral had deteriorated during the long closure and the south tower collapsed later that year. More damage to the tower was caused by a lightning strike in 1642.

After repair a pulpit in early Baroque style was installed, and the pillars and walls were decorated with Renaissance and Baroque epitaphs for cathedral clergy and prominent Bremen citizens. A Baroque altar and canopy were removed in 1839.

Most of the present exterior is the result of late 19th century reworking, including rebuilding of the south tower and the portals with biblical scenes on the doors. A plaque near the entrance acknowledges depictions of Jews in these reflected the anti-Semitic attitudes of the period. In 1912 a cloister attached to the south side was wrecked by fire.

In 1945 a bomb destroyed almost one-third of the building and all the stained glass. Repair and restoration took place in stages from the 1950s to 1970s.

A church and an island in Bremen

Today, the cathedral faces the centre of the market square, part of an array of buildings. But for centuries, it was an island in the centre of the city. From the 9th century it was surrounded by a rounded, roughly triangular barrier and ditch and in the 11th century a stone wall replaced the ditch.

This enclosed a tiny but legally separate territory, untaxed by the city, that included episcopal buildings and residences of the canons and became known as the Domfreiheit.

A paved walkway with a gate led to the market centre, today Am Markt. But within a decade most of the walls were raided for cathedral building stone and there was no effective barrier.

In the late medieval and Renaissance period, the independently minded old town of Bremen was at odds with prince-archbishops of Hamburg-Bremen, leading to occasional violence.

The Swedes took over the territory of Bremen and Verden in 1648 after the Treaty of Westphalia, which ended the Thirty Years War. Under this arrangement the Domfreiheit came under Swedish control and the prince-archbishopric ended, replaced by a duchy.

From 1715 the Domfreiheit switched from Sweden to the authority of Hannover, an arrangement that lasted until 1803, when the it was abolished.

Check out the Raven Travel Guides Europe Bremen travel guide for all the details of Bremen’s leading sights and money-saving tips.

Visiting St Petri Dom

Bremen’s cathedral closes briefly from Monday to Saturday for noon prayers. To reach the cathedral, take tram 1, 2, 3, 4, 6 or 8 to Domsheide. The city’s Böttcherstrasse arts precinct is nearby, as are the chief monuments of Bremen’s medieval and Renaissance past.