Prominences constitute the most complex magnetic structures in the solarcorona. The ubiquitous presence of their seemingly confined dense andcool plasma in an otherwise million-degree environment remains a puzzle.Using a decade of white light total solar eclipse observations, we showhow these images reveal an intricate relationship between prominencesand coronal structures both in their immediate vicinity, known ascoronal cavities, and in the extended corona out to several solar radii.Observations of suspended prominences and twisted helical structuresspanning several solar radii are central to these findings. Thedifferent manifestations of the prominence-corona interface that emerge from this study underscore the fundamental role played by prominences indefining and controlling the complex expansion and dynamic behavior ofthe solar magnetic field in the neighborhood of magnetic polarityreversal regions. This study suggests that the unraveling of prominencesand the outward expansion of the helical twisted field lines linked tothem could be the solar origin of twisted magnetic flux ropes detectedin interplanetary space, and of the mechanism by which the Sun sheds itsmagnetic helicity. This work also underscores the likely role of theprominence-corona interface as a source of the slow solar wind.