1. A user interface for building a formulated query to search a database of structural data organized by classes, attributes of classes, literals of attributes, and structural relations between classes, and for displaying results of the formulated query, the user interface comprising, a structural query section to define constraints for the formulated query, the structural query section including one or more query elements to be populated and a means for adding one or more additional query elements, and wherein a relationship between query elements is expressible using a defined structural relation; and a query results section for displaying results of the formulated query after the formulated query is executed.