The apartment is just in the center. Very close to the Charles Bridge and Old Town Square. Underground station is just around the corner. A perfect place to get by foot to all the tourists points.
The flat was very clean and neat and it's rather large. Despite the busy location there were no noise or dust or traffic fumes from the outside.
The hosts were very friendly, punctual and helpful.
For the future guests the following advice:
Sometimes powercuts occur, so ask the hosts in advance how to turn the electricity on. By the way it's not too complicated.