Note the Australian Pines along what is now Flagler Street.
Thanks to Ray's research, this was the third Dade County Courthouse. The first was in Juno, the second was on the banks of the Miami River and this was the third. The fourth, and current courthouse, occupies the land where this photo was taken.
http://www.miami-dadeclerk.com/dadecoc/Dade_County_Courthouse.asp