We used Prague Local Friends with Ema as our guide. She is a delightful young lady with lots of enthusiasm and love for her city. Full of entertaining stories while pointing out places and tidbits of history along the way. She answered all of our questions, which we had many about the city.
It is a climb UP to the Castle but stops along the way made it very doable. We are in our sixties and had no trouble with the walk. I would consider this a moderate three hour walk. Have to be able to climb some steps and inclines,but so worth the night views. Wear good shoes.
Will use Prague Local Friends and Ema again for future tours They were very quick to response to inquiries and booking.