A review of the many of theunexpected experimental results obtained over the last three years on the low temperature quantum transport properties of sub-micron normal metal samples is presented. Measurementscan now be made on devices where thelithographically patterned distancesbetween measurements probes is much smaller the the characteristic distances over which the conduction electrons maintain their quantum mechanical phase coherence. This in turnhas permitted the discoveries of many new quantum interference effects such as the AharonovBohm effect inhighly disordered conductors, universal conductance fluctuations, and non-local quantum effects. The abilityto vary both the temperature and sample size has yielded information on the effects of averaging these quantum effects over uncorrelated regionsand has shown us to some extent how the transition from quantum to a classical system is achieved. © The Japan Society of Applied Physics.