Plasmonic systems exhibit a host of intriguing optical properties. In this talk I shall assert that the underlying source of this diversity is geometry: that is to say the shape of a plasmonic particle or the structure of a particular surface. I shall show how geometric complexity can be generated starting from simple structures such as waveguides and transforming them into more complex structures, then turning to transformation optics to understand how the properties of the complex structure relate to the simple one. Particular attention will be paid to singular structures which are known to act as harvesters of light and are responsible for the enhanced spectroscopic response that occurs in SERS experiments.