Frank, de Heer et al (Science 280,1744 (1998) found that freely suspended multiwalled carbon nanotubes (MWNTs) are 1-D conductors; the current flows on the outer layer, while large current densities are sustained. Quantized conductance was also found. These findings imply that carbon nanotubes could be ballistic conductors at room temperature. However there are difficulties that need clarification. One is that the conductance is only half what is expected from the theory of single wall nanotubes. Experiments performed on substrate supported and lithographically contacted nanotubes do not (yet) exhibit quantized conductance. Moreover electrical transport in carbon nanotubes is still quite confusing. Our experiments show that the conductance of clean, well-contacted nanotubes is quantized and independent of intercontact distance. Contamination, defects, non-ideal contacts and substrate interactions may explain the discrepancies between our experiments and others.