We came to Gniezno by train from Poznan. We took the slow train for 10 Zlotys on the way there. It took about an hour. Its end destination was actually Torun. I was surprised that the toilet on the train had toilet paper, soap and hand paper.
Make sure you know what time you arrive and look out at the stations as the stops are not announced. We sat towards the front of the train, that way we managed to see the name plates of the stations passing by.
On the way back we took an IC train which took about 40 minutes and cost 14 Zlotys.
Bus tickets in daily fare in Gniezno cost about 0,50 EURO and about 0,25 EURO half fares. They are valid for one ride only.
Tickets can be obtained in most shops in the city as well as from the bus driver with an additional fee.
Bus routes, information about the schedules and bus numbers are placed in buses and on bus stops.
You can find a clickable route map here:
Gniezno is easily accesible by train from Torun as well as from Poznan. The railway station is situated to the south of the city centre, south-east to the cathedral.