The Apollo Applications Program explored missions that would reuse Apollo hardware. Skylab and the Apollo Soyuz Test Project were the result. An unflown concept was a manned Venus mission, which I have rendered here.
The spacecraft was based around the S-IVB, much like Skylab. In many ways, it was the mobile version of the space station. NASA planned three missions, two Earth orbiting practice runs and the shot to Venus.
Meet the Venus Transfer Vehicle (VTV) Venture, humanity's first interplanetary spacecraft in an alternate history. I plan to render the whole program, including the practice missions and the Venus flyby. Here's the Venture over LA.