Prague has a unique means of transport – an old funicular, which goes to the top of the Petřín hill.  
Petřín is a famous hill with a lookout tower on the top, which offers a manificent view of Prague. Additionally, there is a mirror maze by the tower, while the hill itself is covered with gardens and parks. 
You can get to the top of the hill on foot and take a walk through the gardens, nonetheless as a challenge take the funicular instead and enjoy the spectacular view (as a proof take a selfie on the way up). The funicular operates daily from 9 am to 11pm. As it is included in the public transport system you can use your public transport pass or tickets.

Find more useful information on the page of Prague´s Public Transport.