Yes, it is possible if you are well organized… From the Port of Keelung where we docked today there is only 10 min walk to South railway station. Every 20 min they offer a train to Taipei Main station (40 minutes each way – the cost is 62 Taiwan dollars – like 2 USD). Central station in Taipei is like a labirynth – people helped me to find the proped exit to continue walk to the central Square of the capital (picture above) where are theatre and concert hall and yhe memorial of the national hero – general Chang Kai-Shek.
Once in the main station (it has biggest lobby I saw in the world) you can grab the map and walk to the parks with color pavilions and onward to the Chang Kai Chek Memorial – picture above – imposing memorial (Theatre and Concert Hall on the same square) Then I walked some 3 kms to Sun Yat Sen memorial:
Then I ysed blue metro line (20 TD) back to the main station and Keelung. 4,50 USD in total! Great day!