We, a group of 4 seniors are going to be in Berlin from 15th to 18th june. We wouldn't want to miss Reichstag tour , Charlottenburg schloss and Hitler's bunker amongst other things. We are finding non-availability of these tour ton internet during our stay. Are these places accessible without prior reservations or is tgere any way we can arrange beforehand.
Also any advice re local transit commuting and passes will be much appreciated.