In the 18th century, the Spanish Crown ordered the construction of seven defence towers, spread across the entire coast of Ibiza. They were occupied by officials from the Torreros Corps, who scanned the horizon in search of pirates, to alert the residents so that they could run to seek refuge. They also fought them with cast-iron cannons, located on top of these fortresses.
In the Can Planells surroundings, three defence towers are preserved. The closest is the Balansat Tower, on a cliff that rises above the Port de Sant Miquel and the islets of Sa Ferradura and Murada. It was built in 1763 and makes for a spectacular viewpoint towards the Benirràs coast. La d’en Valls, beyond the shores of Es Canal d’en Martí, in Sant Carles, is from the same period. This, however, has been rebuilt, since in 1864 it was half destroyed when the munitions dump exploded by accident. At its feet the Tagomago islet awaits. The third, contemporary to the previous ones, awaits in Portinatx and is awaiting restoration.