What IT Was

Thank You, SM, for your valiant attempt to guess what the ruins near the Bracui Marina represent.  As with you, its grandeur and style suggested to me some religious institution, such as a seminary, convent, or perhaps an ordinary school.

Although the ruins have been preserved, there is no plaque describing their history, so I asked Ricardo, my boating neighbor.  His answer is perhaps an indicator of the attitude and priorities of early Brazilian society.  

The ruins are of a sugar mill dating back to the 19th century.  I commented to Ricardo that it must have been one large mill, and according to him it was a large operation and Bracui (still referred to as Porto Bracuhy) was a busy port.  The sugar milling operations have moved to the north and are heavily mechanized, rendering the mill and port of Bracui a historical footnote.