Twin Cape

Twin Cape (双子岬) is located at the bottom of Reverse Mountain, at the exit that leads into the Grand Line. The areas is located precisely where the Red Line and the Grand Line meet. From this place it's also possible to choose one of the seven routes of the Grand Line by waiting the Log Pose to set on the desired one.

Lighthouse
The lighthouse is a located after entering through Reverse Mountain, where one can find information about the dangers of the Grand Line. This is the where the Laboon Arc took place. Crocus resides here for about 50 years taking care of Laboon, minus the three years he spent as the doctor of the Roger Pirates.