The Supreme Court looks at Notre Dame in Paris as an example of how a religious monument can become an important secular monument.

In today's opinion, American Legion v. American Humanists Association, about a large cross memorializing WWI dead, Justice Alito wrote for the majority:

With sufficient time, religiously expressive monuments, symbols, and practices can become embedded features of a community’s landscape and identity. The community may come to value them without necessarily embracing their religious roots. The recent tragic fire at Notre Dame in Paris provides a striking example. Although the French Republic rigorously enforces a secular public square, the cathedral remains a symbol of national importance to the religious and nonreligious alike. Notre Dame is fundamentally a place of worship and retains great religious importance, but its meaning has broadened. For many, it is inextricably linked with the very idea of Paris and France. Speaking to the nation shortly after the fire, President Macron said that Notre Dame “‘is our history, our literature, our imagination. The place where we survived epidemics, wars, liberation. It has been the epicenter of our lives.’”