The Forte dos Andradas occupies a dramatic headland at Morro do Monduba, overlooking the southern entrance to the Santos Channel. The fortress dates to the 17th century, when the Portuguese needed to defend their richest port from pirates and rival colonial powers. The original walls are still largely intact.
Today the fort is an active military installation, which limits public access, but the surrounding headland and its views over the channel and open Atlantic are accessible and worth the trip to the southern end of the island. The drive out passes through quieter parts of Guarujá away from the beach crowds.