Tour round and round the building (7)
I believe the answer is:
rotunda
'the building' is the definition.
(rotunda is a kind of building)
'tour round and round' is the wordplay.
'round' indicates anagramming the letters.
'round' indicates anagramming the letters.
'tour' is an anagram of 'rotu'.
'and' is an anagram of 'nda'.
'rotu'+'nda'='ROTUNDA'
(Other definitions for rotunda that I've seen before include "Round building or hall" , "Italian Pantheon, for instance" , "Circular room or building" , "Round domed building" , "Circular building with a dome" .)