With the rapid growth in popularity of social websites, social event detection has become one of the hottest research topics. However, continuously monitoring social events has not been well studied. In this demo, we present a novel system called EventEye to effectively monitor evolving events and visualize their evolving paths, which are discovered from tweet streams. In particular, four event operations are defined for our proposed stream clustering algorithm to capture the evolutions over time and a multi-layer indexing structure is designed to support efficient event search from large-scale event databases. In our system, events are visualized in different views, including evolution graph, timeline, map view, etc.