A hierarchical structure and physical component of an APEX^™ 20K, APEX^™ II, or ARM^®-based Excalibur^™ device. Each APEX 20K, APEX II, or ARM-based Excalibur device is made up of a series of these structures, organized in rows and columns. Each MegaLAB^™ structure contains 16 LABs (24 LABs for 20K1000E, 20K1500E, EP2A40, and EP2A70), one Embedded System Block (ESB), and a MegaLAB interconnect, which routes signals within and into, but not out of, the MegaLAB structure. Signals are routed between MegaLAB structures and to I/O pins via the FastTrack^® interconnect and/or the local interconnect. A shared local interconnect also connects the logic elements within the same LAB and between adjacent LABs.