Quantum computers may revolutionize the field of computation by solving some complex problems that are intractable even for the most powerful current supercomputers. This paper first introduces the basic concepts of quantum computing and describes what the required layers are for building a quantum system. Thereafter, it discusses the different engineering challenges when building a quantum computer ranging from the core qubit technology, the control electronics, to the microarchitecture for the execution of quantum circuits and efficient quantum error correction. We conclude by discussing some compiler and programming issues relative to quantum algorithms.