On March 17th the Skylon Tower in Niagara Falls Canada will be illuminated green in honour of St Patrick's Day.
St Patrick's Day has been observed since the 17th century. In Canada it has been an observance in North American ( except for Newfoundland where it is Holiday) for decades. It is celebrated around the world more than any other national festival. Green is the recognized colour for St Patrick's Day, many world landmarks including the Skylon Tower are turned green to celebrate the occasion.