There is a beautiful Irish tradition that is very popular in the United States. I know you have seen those candles in the windows at Christmas. The placing of a lighted candle in the window of a house on Christmas eve is still practiced today. It has a number of purposes but primarily it was an symbol of welcome to Mary and Joseph as they traveled looking for shelter.
The candle also indicated a safe place for priests to perform mass as, during Penal Times this was not allowed.
A further element of the tradition is that the candle should be lit by the youngest member of the household and only be extinguished by a girl bearing the name "Mary".