Single-walled carbon nanotubes (SWNTs) uniquely combine characteristics of polymers (e.g., they are molecules composed of repeat units) as well as nanoscale colloids (e.g., they are extremely stiff); because of these characteristics, they may qualify as the ideal building blocks for the long-sought Staudinger's "continuous crystal." To this end, neat SWNT fibers have been produced by wet-spinning concentrated dispersions of 6-10 wt % SWNTs in 102% H 2 SO 4 . A unique protocol that combined UV-ozone dry chemical etching and cryoultramicrotoming was developed to directly visualize the internal voids, alignment, and composition of these SWNT neat fibers. A substructure of large aligned SWNT ropes, 200-500 nm in diameter, was revealed throughout the fibers. This substructure may be linked to the SWNT spaghetti, threadlike liquid-crystalline domains observed in dispersions of SWNTs in H 2 SO 4 .