Generally discussed herein are systems, devices, and methods that include an organic high density interconnect structure and techniques for making the same. According to an example a method can include forming one or more low density buildup layers on a core, conductive interconnect material of the one or more low density buildup layers electrically and mechanically connected to conductive interconnect material of the core, forming one or more high density buildup layers on an exposed low density buildup layer of the one or more low density buildup layers, conductive interconnect material of the high density buildup layers electrically and mechanically connected to the conductive interconnect material of the one or more low density buildup layers, and forming another low density buildup layer on and around an exposed high density buildup layer of the one or more high density buildup layers.