The exponential growth in mobile data exchange rates, which is further augmented by the rapid proliferation of mobile devices, significantly increases the capital and operational expenses of the cellular network operators. Growing expenditures combined with environmental awareness have driven the network operators to provide more energy-efficient services and reduce their carbon dioxide footprint by using green networking methods. In this paper, we focus on green dynamic base station (BS) topology management according to the varying traffic conditions for the next-generation heterogenous cellular networks. We first create a detailed 3-D map of a selected pilot application area in order to obtain a realistic spatio-temporal user density estimation. Then, we formulate a novel optimization problem to find the best possible topology, which minimizes the overall network power consumption while satisfying quality-of-service requirements of the subscribers. As an additional problem, we derive a pico BS deployment methodology on top of the existing network infrastructure to accommodate the peak traffic conditions. Finally, we propose offline-centralized and online-distributed green dynamic BS operation algorithms for power saving during the operation phase. Extensive simulations based on a realistic and a random test case scenario show that our dynamic BS topology management methods achieve significant power savings compared with static operation.