Known to the Portuguese as Fort Malayo, the Dutch-built Benteng Oranye, which dates from the early 17th century, is a sprawling, largely-ruinous complex inhabited by goats, rusted cannon and…the army. Once home to the Dutch governor, it's now overgrown, neglected and (in parts) unsympathetically concreted. You can still wander some sections of cannon-topped bastion, accessed through a restored gateway arch, and its current tenants (the army, not the goats) are aiding efforts to restore some of its former grandeur.