In recent years, numerical fracturing simulation has seen an unprecedented emphasis on capturing the complexities that arise in hydraulic fracturing to better design and execute hydraulic fracturing jobs. As the need for more sophisticated simulators grows, so does the need for more sophisticated physical models that can be used to study the mechanics of the fracturing process under a controlled environment, and to validate the numerical predictions of advanced hydraulic fracturing simulators. We developed and utilized novel laboratory capabilities to perform an extensive set of fracturing experiments across various aspects of hydraulic fracture propagation including the effect of far-field stress contrast, rock mechanical heterogeneity, multi-well injection, borehole notching, fluid injection method, type of injection fluid, and interaction with natural fractures. Numerous direct observations and digital image analyses are documented to provide fundamental insights in hydraulic fracturing. As demonstrated through a few case studies from the literature, our laboratory experiments are very useful for validating hydraulic fracturing simulators due to the small-scale, two-dimensional (2-D) nature, controlled environment, and well-characterized properties of the test specimens used in the experiments.