The Old Caoling Tunnel, located in New Taipei City, Taiwan, is a historic railway tunnel that was once the longest in Southeast Asia. Built in 1924, it played a crucial role in transporting people between Taipei and Yilan. Today, it has been transformed into a unique bikeway, allowing visitors to walk or ride their bikes through its cool and nostalgic atmosphere. With its retro oil lamp lighting and train sound effects, it's like stepping back in time. Plus, you can't miss the stunning view of the Pacific Ocean and Turtle Island as you pedal your way through this 20-kilometer-long circular bikeway. It's definitely a must-visit spot for bike enthusiasts and history buffs alike!