Fort Frederick, also known as Trincomalee Fort, is a historic fort in Sri Lanka that was originally built by the Portuguese in 1624. It was constructed using materials from the destroyed Koneswaram temple and later rebuilt by the Dutch in 1665. Over the years, it changed hands between various colonial powers until it became a British garrison. Today, it is still used by the Sri Lankan Army and is open to visitors who can explore its rich history and stunning views.