[1] Pope Pius XI raised Speyer Cathedral to the rank of a minor basilica of the Roman Catholic Church in 1925.

[2] As the burial site for Salian, Staufer and Habsburg emperors and kings the cathedral is regarded as a symbol of imperial power.

[9][10][11] In 1981, the cathedral was added to the UNESCO World Heritage List of culturally important sites as "a major monument of Romanesque art in the German Empire".

[2][12][13][14] In 1025, Conrad II ordered the construction of the Christian Western world's largest church in Speyer which was also supposed to be his last resting place.

Construction began in 1030 on the site of a former basilica which stood on an elevated plateau right by the Rhine but safe from high water.

[2][17] Around 1090, Conrad's grandson, Emperor Henry IV, conducted an ambitious reconstruction in order to enlarge the cathedral.

The nave was elevated by five metres and the flat wooden ceiling was replaced with a groin vault of square bays, one of the outstanding achievements of Romanesque architecture.

Engaged shafts had appeared around 1030 in buildings along the Loire (Saint-Benoît-sur-Loire, Auxerre, Loches) from where the technique spread to Normandy and the Rhineland.

At the east end of Speyer Cathedral the dwarf gallery and the blind arcades were composed into "one of the most memorable pieces of Romanesque design".

[4] The building became a political issue: the enlargement of the cathedral in the small village of Speyer with only around 500 inhabitants was a blunt provocation for the papacy.

The emperor not only laid claim to secular but also to ecclesiastical power, and with the magnificence and splendour of this cathedral he underlined this bold demand.

The purpose of the building, already a strong motive for Conrad, was the emperor's "claim to a representative imperial Roman architecture" in light of the continuing struggle with Pope Gregory VII.

When relations between the pope and German king were good, they were crowned "Imperator Romanum" or Holy Roman Emperor.

[12] In the great fire the Prince-Bishops of Speyer lost their residence and a plan was considered to build a new one in the style of a Baroque château in place of the cathedral.

At the behest of King Ludwig I of Bavaria, Johann von Schraudolph and Joseph Schwarzmann decorated the interior walls of the cathedral with Nazarene style frescoes (1846–1853).

1854 to 1858, Ludwig's successor, King Maximilian II, had the Baroque westwork replaced by a Neo-Romanesque one, with the two tall towers and the octagonal dome resembling those that were lost, thus restoring the cathedral's overall Romanesque appearance.

In designing the façade of the westwork, Heinrich Hübsch, an architect of early Historicism, created a Neo Romanesque design which drew on features of the original westwork and those of several other Romanesque buildings, scaling the windows differently and introducing a gable on the facade, a row of statues over the main portal and polychrome stonework in sandstone yellow and rust.

In 1916, Georg Dehio, a German art historian, was convinced that among all the misfortunes to befall the cathedral, the alterations of the 19th century were not the smallest.

Gables which had been removed from the transept and choir during the Baroque era were replaced using etchings and examples in related buildings.

[25] Speyer Cathedral has maintained the overall form and dimensions of the 11th-century structure and, despite substantial losses to the original fabric and successive restorations, presents a complete and unified Romanesque building.

The design broadly follows the plan that was established at St. Michael's Church in Hildesheim and set the standard that was to be generally adopted in the Rhineland.

The western end terminates in an elaborate structure known as a "Westwerk" including the main portal, a feature typical of many Romanesque churches.

The nave, towers and domes are all roofed with copper, which has weathered to pale green, in contrast to the pinkish red of the building stone, and the polychrome of the Westwerk.

Although most of the plasterwork of the 19th century has been removed from wall surfaces, the wide expanse of masonry between the arcade and the clerestory contains a series of colourful murals depicting the Life of the Virgin.

In April 1981, Speyer Cathedral was added to the UNESCO World Heritage List of culturally important sites.

The sandstone blocks alternate in colour between yellow and rust, a typical design of the Salian and Staufer era, and providing the context of the colour-scheme of the 19th century facade.

The "architectural clarity is quite exceptional, a result of the precise execution of the base moldings and the cushion capitals, together with the emphatic system of transverse arches.

Saint Mary's chapel had been added on the northern side of the cathedral by Bishop Matthias von Rammung in 1475.

[25] The cathedral's peal is composed of nine bells of which the larger four were cast in 1822 by Peter Lindemann (Zweibrücken) and the five smaller ones in 1963 by Friedrich Wilhelm Schilling (Heidelberg).

The sculpture of the Mount of Olives was destroyed in the great fire of 1689 and left in ruins after the rubble of the cloister was removed in 1820 in order to create some open space.