ENIAC

Between in 1943-1946, John P. Eckert and John Maunchly created the ENIAC (the successor was the EDVAC) in 1946, which was used to calculate artillery for the US military. The program was used for solving large, numerical problems through reprogramming.
This machine has been regarded as the first programmable computer. Standing for Electronic Numerical Integrator and Computer.
This device was the predecessor to all electric computers that we use today, as well as being regarded as the first general computer. With the ENIAC being made from 17,500 vacumms, it costed over 500k to make.