From Main train station, take Metro C (red line) to Muzeum station and change to Metro A (green line) and go to Staroměstská station [staromyestska:]. Then it is just about 200 m walk. From the Main train station, you can also walk to Muzeum station.
From the Main train station, you need to walk straight across the park and then take Jeruzalémská street until the end. Go slightly left, walk through the underpass and take Senovážná street and at the end, you need to take Celetná street. It is on the left behind the Powder Tower. When you reach the Old town square, you need to walk across and take the far left street behind St. Nicholas church. You will then be at Franz Kafka square and we are located just twenty meters straight between the Exchange and Pizza/gyros fast food on the right-hand side.