This 17th century palace, adjoining the Basilica, and originally built in a rectangular shape with two courtyards inside, remained unchanged until Johannes Seitz, rebuilt the south-wing 1757-61 in the style of this period, to make it the Elector's official residence. But this project was never completed and the balance of its proportions was seriously impaired by the Basilica's subsequent restoration during the middle of the last century. Its truly magnificent inner staircase is the work of the sculptor Ferdinand Tietz from Upper Frankonia and his playful ease in using to the utmost all possibilities of his art to give expression to his sparkling imagination borders on the unbelievable. The figures on the balcony and on the pediment - Ceres, the Goddess of Agriculture and Fertility, the Putti and Graces - are all his or his school's work. The Palace is now the seat of the District Government and Administration.
The buildings in the second palace courtyard were damaged or destroyed in 1944 and later partly replaced by new buildings. Der Rote Turm (Red Tower) dating from the middle of the 17th century was restored here in 1966/67.
The brick building of the Aula Palatina - now named Basilica - dating from the period of Constatine the Great, approximately 310 A.D., and the Elector's Palace, partly Renaissance and partly Baroque in style, are now linked into one single and expansive architectural unit. This merger is a natural process in that it results from its uninterrupted use through the centuries, further indicated by the fact that all records invariably and without fail use its traditional name of "Palatium".
The Roman Palace's west wall and apse, dating from 310 A.D., built over a demolished palace of much smaller size whose foundations are recognizable underneath the later building, still stand at almost their original height (the wall's thickness is 2.30 - 3.40m). The interior of the gigantic hall (height 30m, width 27m and length 67m) - despite its dimensions perhaps only a sort of appendix to the Imperial residence proper - had been richly decorated with mosaics and marbles and the outside walls were well plastered and fitted along their whole length with a gallery underneath its windows (these were 7m high and 3.50m wide).
At the beginning of the 17th century, part of the building was pulled down (east -and south walls), and the remainder incorporated in the Renaissance Palace of the Prince Electors of Trier.
Following the Electorate's dissolution, e.g. during the neo-Romantic period (1846 - 56), it was rebuilt and since then, houses a Protestant church. Yet, the effect created by a building of such dimensions and, above all, the deep and lasting impression of its interior, remained unimpaired, and perhaps, the particular of the restoration work carried out after the sever damages of the last war, even deepened such impressions of magnificence and grandeur.