MTR
It is interesting to note that since the line's opening in 1982, this is the only line whose alignment has virtually remained the same for the past 23 years. For example, the Kwun Tong Line's alignment has changed for 2 times since its opening - the taking over of Tsuen Wan Line from Mong Kok to Central, and the taking over of Eastern Harbour Crossing section by the Tseung Kwan O Line.