Timelines are often used for summarizing complex, time-evolving, sequences of events. In this work, we propose Linea, a tool that helps users build timelines from unstructured text. Besides providing interactive tools for browsing, selecting, editing, and filtering events, Linea includes mechanisms to build smart defaults, thus providing good starting points for users to create their own timelines. The core component is a novel visualization widget called event matrix, a matrix designed to explore events over time and in different time scales. We illustrate the strengths of our tool with a case study showing that important events can be browsed, timelines can be easily built, and show the result of an information user evaluation.