Market players that can respond to critical business events faster than their competitors will end up as winners in the fast moving economy. Event-based systems have been developed and used to implement networked and adaptive business environments based on loosely coupled systems. In this paper, we introduce Event Cloud, a system that allows searching for business events in a variety of contexts that also take the relationships between events into consideration. Event Cloud supports knowledge workers in their daily operations in order to perform investigations and analyses based on historical events. It enables users to search in large sets of historical events which are correlated and indexed in a data staging process with an easy-to-use search interface. For improving the search results, we propose an index based ranking system. We present an architecture for the Event Cloud system, which supports a continuous near real-time integration of business events with the aim of decreasing the time it takes to make them available for searching purposes. We have fully implemented the proposed architecture and discuss implementation details.