* The Posadas: This is the most common way to refer to it, using the Spanish term but making it clear it's a specific event.
* The Pilgrimage of the Posadas: Emphasizes the religious aspect and the journey.
* The Posadas Festival: Focuses on the festive nature of the celebration.
* The Christmas Posadas: Highlights the timing and connection to Christmas.
You could also explain it further by saying:
* The traditional Mexican Christmas celebration where people reenact the journey of Mary and Joseph looking for lodging.
* A nine-night procession and celebration in Mexico that commemorates the journey of Mary and Joseph.
Ultimately, the best way to say "las posadas" in English depends on the context and what you want to emphasize.