Just south of the downtown area of Miami (in the Brickell area) sits this beautiful old neighborhood full of Royal Poinciana trees. The street is Miami Avenue and travels north directly through Miami. The houses have always been "expensive". Now, they are taking down the older, smaller homes and replacing them with the big box mansions.
I was just reading the Mary Brickell (one of the founders of Miami) platted the Brickell area as an area for mansions. Apparently, it is known as Millionaire's Row. While none are currently for sale on Miami Avenue, one built in 1953 nearby is under contract at $3.5 million.