A method of designing a 3D Integrated Circuit, including: performing partitioning to at least a logic strata, the logic strata including logic, and to a memory strata, the memory strata including memory; then performing a first placement of the memory strata using a 2D placer executed by a computer, where the 2D placer includes a Computer Aided Design tool, where the 3D Integrated Circuit includes a plurality of connections between the logic and the memory strata; and performing a second placement of the logic strata based on the first placement, where the memory includes a first memory array, where the logic includes a first logic circuit connected so to write data to the first memory array, where the first placement includes placement of the first memory array, and where the second placement includes placement of the first logic circuit based on the placement of the first memory array.