I can provide information about the historical significance of Nicaea and past popes named Leo, but since Pope Leo XIV is a future pope, I cannot provide information about his potential visit to Nicaea.

Here's some background information that may be helpful:

Historical Significance of Nicaea

• First Ecumenical Council: Nicaea is best known as the location of the First Ecumenical Council in 325 A.D. 1 2. This council was convened by Emperor Constantine to address the Arian controversy, which questioned the divinity of Jesus Christ 1 2.
• Nicene Creed: The council produced the Nicene Creed, a foundational statement of Christian belief that affirms the divinity of Jesus Christ, declaring him to be "God of God, Light of Light, very God of very God, begotten, not made, being of one substance with the Father" 3. The Nicene Creed defines that Jesus Christ is consubstantial with the Father 3. It also anathematizes those who deny the divinity of Christ 4.
• Other Matters: Besides the dogmatic question, the Council of Nicaea also addressed disciplinary issues, such as the Melitian schism, and established canons concerning church governance and practices 2 4 5 6 7.

Popes Named Leo

There have been thirteen Popes named Leo. Here's a brief overview of a few:

• Leo V: His papacy in 903 A.D. was one of the shortest in history, during a time of political instability in Rome 8. He was deposed after a few months 8.
• Leo VI: Reigned from 928 to 929, during a period of political instability. His papacy was marked by efforts to maintain order amid factionalism among the Roman nobility and threats from external forces 9.
• Leo VII: He reigned from 936 to 939, and is remembered as a figure of relative stability during a time of political turmoil in the Roman Church 10.
• Leo VIII: His election followed the deposition of Pope Benedict V by Emperor Otto I, and his papacy was marked by his attempts to navigate the complex dynamics of Roman politics while asserting the authority of the papacy 11.
• St. Leo IX: He served from 1049 to 1054 and was a reformer in the Catholic Church 12. He is known for his efforts to address corruption within the Church, particularly simony and clerical marriage 12.
• Leo X: Reigned from 1513 to 1521 and is known for his patronage of the arts and his role during the early stages of the Protestant Reformation 13.
• Leo XIII: His pontificate was from 1878 to 1903 14. He is celebrated for his efforts to engage the Catholic Church with the modern world, notably through his encyclical Rerum Novarum, which addressed the rights and conditions of workers 14. He sought to reconcile faith with reason and was an advocate for education, dialogue with contemporary society 14.