Probably the most reliable mean of transport in Bangkok... I recommend finding a place to stay closeby if you don't want to waste time in traffic. It's cheap, fast and can take you to many places in the capital.
Let me tell you, I am no train spotter, but seeing the train at three spots at once, was pretty amazing! We could see it down at the bottom of the hill and then wind up and enter the spiral tunnel and then come out above at the top of the tunnel - all at once! My husband had to drag me to watch it, but it was really fun to see.
Of more than 2,500 National Historical Landmarks, only two can (willfully) move: San Francisco's cable cars and New Orleans’s St. Charles streetcar line. Source: The New Orleans
We walked up Narikala Fortress and were meant to walk down too but the rain started so we decided to use the cable car. It's quick and pleasant, there are nice views from the inside too.