The images on this denarius are a pun on the name of the moneyer. He was called Petillius Capitolinus, hence he depicted on the obverse the head of Jupiter and on the reverse his temple on the Capitoline Hill.
Jupiter Optimus Maximus was the highest of the Roman gods; his Greek equivalent was Zeus. Jupiter had his temple on the Capitoline Hill in Rome, and was therefore also called Jupiter Capitolinus.
Legend had it that the temple of Jupiter Capitolinus had been projected around 600 BC by the Roman king Tarquinius Priscus, but was finished and consecrated only about a century later. More than 400 years after that the temple of Jupiter Capitolinus was destroyed by a fire. It was rebuilt and reconsecrated in 69 BC.