Majority of the available digital information are associated with some location or regions on the Earth.  Traditional visual interfaces to digital libraries were not designed to deal with the unique geospatial characteristics of data, nor did they take full advantage of the georeferencing as a mechanism for browsing and retrieving information.   This paper highlights the trends of visual interfaces to geospatial information, and suggests major challenges towards effective visualization of multimedia geospatial document space.  Citing recent research efforts, we review the attempts to integrate document visualization (developed in information science) with geovisualization techniques (developed in geographical information science) to support science, information access and decision making.   We conclude by a set of spatial cognitive principles that influence future development of such visual interfaces to geographic information.