This paper addresses the issues of building Virtual Laboratory environments and presents architecture of VL-E - a Grid-enabled virtual laboratory being developed at University of Amsterdam. The Virtual Laboratory concepts are usually described as having the objective to bridge the gap between the application layer and lower layers that compose the infrastructure needed to support these applications. In the Grid environment the core layer of middleware is usually provided by toolkits like Globus ([Foster and Kesselman, 1998]) that enable low-level functionality and encourage building higher level toolkits that would offer new facilities, such as a robust access to different management facilities, adequate fault tolerance in distributed systems, reliable super-scheduling techniques, workflow support, web portal technology, advanced information management techniques and virtual reality visualization. Here we present a structural overview of VL-E and discuss some related issues brought up by nature of Grid environment.