Mainz Cathedral is predominantly Romanesque in style, but later exterior additions over many centuries have resulted in the appearance of various architectural influences seen today.

The interior of the cathedral houses tombs and funerary monuments of former powerful Electoral-prince-archbishops, or Kurfürst-Erzbischöfe, of the diocese and contains religious works of art spanning a millennium.

In 975–976 shortly after his installation he ordered the construction of a new cathedral in the pre-Romanesque Ottonian architecture style.

During renovations ordered by Henry IV in the late 11th century, much of the outside was also plastered, but the cornices were left exposed in their original red and yellow.

From the ninth to 12th century, several important churches in the Holy Roman Empire were built with choirs on both ends.

This type of footplans also was acquired in Poland (Tum Collegiate Church) and Hungary (Pécs Cathedral).

Many scholars suggest that there is some symbolic significance, such as empire and church, or body and spirit, but no irrefutable evidence for these theories exists.

Willigis, however, designed his cathedral with the main chancel on the west, presumably modeled after the great basilicas in Rome, which were constructed this way.

(Willigis's remains are not, as sometimes believed, in Mainz Cathedral; he was buried in his second construction project, St.

The old flat chancel end on the east side was replaced with a large apse, which external gallery with a narrow arcade supported by short columns crowned the semicircular wall with a wide pseudo arcade and tall pilasters on both sides.

These changes closely resembled the renovations Henry had overseen on Speyer Cathedral a few years earlier.

Henry also undertook a few other minor changes, such as raising the transept on the east side and adding openings at the column level.

This time, however, without money from the emperor, the builders lacked the resources to acquire the high-quality sandstone used in Henry's additions.

The other aspects of the renovations were also much cheaper, and the extravagant style of Speyer Cathedral was largely avoided.

It seems that the blind arches were intended to encompass the windows, as in Speyer Cathedral, but the height of the roof did not allow this.

Around the time that the ribbed vault was installed it was decided to renovate the western half of the cathedral, which had stayed relatively unchanged since Willigis' construction.

Starting in 1279, Gothic chapels featuring large decorative windows were built onto the cathedral.

All the towers in the western wing were roofed with this new Baroque stone design, although care was taken to preserve the previous styles as well.

This attack damaged large portions of the cathedral, particularly the east wing, the cloister, and the Liebfrauenkirche, which was demolished in 1803 (the year after Mainz lost its archbishopric and became a regular diocese).

Bishop Joseph Ludwig Colmar (1802–1818), with support from Napoleon, set into motion restoration efforts.

These efforts were interrupted by quartering needs for the French Army in 1813, and the cathedral was used as a church in 1814 for the first time in eleven years.

The major change to the building was an iron cupola on the main eastern tower built by architect Georg Moller.

Large and colorful Nazarene movement murals, including some by Philipp Veit, were painted to decorate the inside of the cathedral.

After a lowering of the groundwater, the wooden substructures became rotten and the foundations started to fail and needed to be replaced.

Architect Paul Meyer-Speer engineered a system to modify the inner walls with colorful sandstone, removing most of the paintings by Veit and restoring a look similar to the original Willigis-Bardo construction.

In World War II, Mainz was a target of Allied bombing multiple times.

It was from this cathedral that Frederick Barbarossa, the Holy Roman Emperor of the time, officially announced his support for the Third Crusade during the Curia Christi of 27 March 1188.

The crowning in Mainz awarded the monarch the kingdom of Germany, and a subsequent in Rome granted him the Holy Roman Empire (a nominal difference only).