Fort Nepean is a historic coastal fortification located at the entrance of Port Phillip Bay in Victoria, Australia. Built in the late 19th century, it was designed to protect the bay from potential naval threats. The fort features a series of gun emplacements, tunnels, and observation posts, showcasing military architecture from that era. Today, Fort Nepean is part of the Mornington Peninsula National Park and is accessible to the public. Visitors can explore the fort's structures, enjoy scenic views of the bay, and learn about its history through informative displays and guided tours.