The beauty of biological systems is that cells as diverse as human muscle cells and growing plants cells are composed of the same basic set of macromolecules such as proteins, lipids and DNA. Common cellular macromolecules form membrane-bound organelle structures found in all cell types and the concept that a closed organelle system contains specialized biochemical functions is well accepted. An emerging and more revolutionary concept is that areas of the cell that are between organelles, as a consequence of their nanostructure, are also structurally specialized regions of distinct and important functions. Conceptually, the specific three dimensional architecture of the nanospace allows strategically positioned selected transport molecules to convert random thermal motion into directed flow, enabling reactions that would otherwise be energetically unfavourable. Biological nanospaces vary in width from a few to about 50 nanometres and are situated between apposing membranes within the cell, but are contiguous with the cytosol, which differentiates them from membrane delimited organelles. This introduction will address the importance of cytoplasmic nanospaces in Ca2+ transport and site and function specific signalling in smooth muscle. It will begin with a historical perspective on the study of the junctional space between the plasma membrane and the peripheral sarcoplasmic reticulum (SR), including experimental evidence for its role in the generation of asynchronous cytoplasmic Ca2+ waves. Subsequently a number of other critically important nanospaces, which are located between the SR, caveolae, mitochondria, lysosomes and other endosomes will be discussed. Finally it will be considered how loss of nanospace ultrastructure may lead to smooth muscle dysfunction and disease.