The ability to highly localize light with strong electric field enhancement is critical for enabling higher-efficiency light sources, modulators, and solar cells, and can dramatically enhance nonlinear properties. While deep-subwavelength modes can be realized with plasmonic resonators, large losses in these metal structures preclude most practical applications. In this presentation, we discuss an approach enabling two levels of spatial localization of photons in a dielectric material, leading to the demonstration of a silicon bowtie photonic crystal structure that supports mode volumes commensurate with plasmonic elements and quality factors that reveal ultralow losses. Both the electromagnetics principles underlying the design of the bowtie photonic crystal and potential applications of the structure will be addressed.