In 1584, the coast of Mallorca was protected by eleven fortified towers against the marauding assaults of the pirates and the corsairs. The Torre de Portopetro was built a few years later, during the early 17th century. Of course, at that time the pueblo of Portopetro did not even exist. The area was then know as the Predio Sa Punta, which belonged to the Danús family from Santanyí.
A very nice drawing of Sa Torre de Portopetro exists and is known to be by the hand of the Austrian Archiduque Luis Salvador. It was first published in 1897, in the book Die Balearen (volume 1) and is copied below. It would seem to me that the tower was taller in the old days, possibly extending over three storeys.
The tower can be visited but, opening hours seem to be few and far between. I have not managed to gain entrance myself as yet.
The photo (top) was chosen from my archive. It was taken in Portopetro, Mallorca, Baleares, Spain. The date: December 1st, 2008. The time was 13:06:16. The image (bottom) was taken from the Internet. Thanks are due to Alta mar and fabian.balearweb.net.