Wittenberg is a district () in the east of Saxony-Anhalt, Germany. Neighboring districts are (from west clockwise) Anhalt-Bitterfeld, the district-free city of Dessau-Roßlau, the districts of Potsdam-Mittelmark, Teltow-Fläming and Elbe-Elster in Brandenburg, and the district of Nordsachsen in the Free State of Saxony.
Although there had been significant earlier attempts to reform the Catholic Church before Luther -- such as those of Jan Hus, Peter Waldo, and John Wycliffe -- Martin Luther is widely acknowledged to have started the Reformation with the Ninety - five Theses. Luther began by criticising the sale of indulgences, insisting that the Pope had no authority over purgatory and that the Catholic doctrine of the merits of the saints had no foundation in the Bible. The Protestant Reformation, however, would come to incorporate doctrinal changes such as a complete reliance on Scripture as a source of proper belief (sola scriptura) and the belief that faith in Jesus, and not good works, is the only way to obtain God's pardon for sin (sola fide). The core motivation behind these changes was theological, though many other factors played a part, including the rise of nationalism, the Western Schism that eroded loyalty to the Papacy, the perceived corruption of the Roman Curia, the impact of humanism, and the new learning of the Renaissance that questioned much traditional thought.
Despite Martin Luther's harsh polemics against his Roman Catholic opponents over issues concerning Mary and the saints, theologians appear to agree that Luther adhered to the Marian decrees of the ecumenical councils and dogmas of the church. He held fast to the belief that Mary was a perpetual virgin and the Theotokos or Mother of God. Special attention is given to the assertion that Luther, some three-hundred years before the dogmatization of the Immaculate Conception by Pope Pius IX in 1854, was a firm adherent of that view. Others maintain that Luther in later years changed his position on the Immaculate Conception, which, at that time was undefined in the Church, maintaining however the sinlessness of Mary throughout her life. For Luther, early in his life, the Assumption of Mary was an understood fact, although he later stated that the Bible did not say anything about it and stopped celebrating its feast. Important to him was the belief that Mary and the saints do live on after death. "Throughout his career as a priest-professor-reformer, Luther preached, taught, and argued about the veneration of Mary with a verbosity that ranged from childlike piety to sophisticated polemics. His views are intimately linked to his Christocentric theology and its consequences for liturgy and piety." Luther, while revering Mary, came to criticize the "Papists" for blurring the line, between high admiration of the grace of God wherever it is seen in a human being, and religious service given to another creature. He considered the Roman Catholic practice of celebrating saints' days and making intercessory requests addressed especially to Mary and other departed saints to be idolatry. His final thoughts on Marian devotion and veneration are preserved in a sermon preached at Wittenberg only a month before his death:
Vincentas Sladkevičius, MIC (20 August 1920 – 28 May 2000) was a Lithuanian Cardinal of the Roman Catholic Church. He served as Archbishop of Kaunas from 1989 to 1996, and was elevated to the cardinalate in 1988.

Question: Where is the district that the person who wanted to reform and address Vincentas Sladkevičius' religion preached a sermon on Marian devotion before his death located?
Answer: Saxony-Anhalt