21 nor will they say, 'Look, here it is!' or, 'There it is!' For behold, the kingdom of God is in your midst." "
21Neither shall they say, Lo here! or, lo there! for, behold, the kingdom of God is within you.
The King James Version
Heaven is biblically located "above". What is being refered to in this scripture is the kingdom of god. Kingdoms consist of a King and his people, what's being said would appear to more of a clarification than the introduction of a new mystery concept. Kingdom does not always refer to a location or bounds of a country.