An extensible three dimensional circuit having parallel array channels includes an access layer and crossbar array layers overlying the access layer and being electrically connected to the access layer. The crossbar array layers include parallel channels, the parallel channels being formed from two classes of vias, the first class being pillar vias connected to relatively short stub lines, and the second class being traveling-line vias connected to long lines that travel away from the via; pillar vias and traveling-line vias being configured to connect to crossing lines such that each crossing point between the lines is uniquely addressed by one pillar via and one traveling-line via. Programmable crosspoint devices are disposed between the crossing lines.