Is there a God? It's an eternal question that all ancient civilizations have answered. Not with just one God, but with hundreds of them. Bringing them to life on earth, these civilizations fashioned their images in wood, paint and stone. And built spectacular holy shrines to house them.

So what happened to these Gods? Do powerful faiths just vanish? Can Gods die? Are these once sacred sites the final resting places for long-lost religions? And how can people who believed in so many deities for so long come to believe in just one and sweep the others to extinction?

The Egyptians. The ancient Egyptians were obsessed with divinity, death and the afterlife and reincarnation. Kenneally visits Saqqara, south of Cairo, where the Egyptians learned the technique of mummification and built the first pyramid, an early prototype for the grand monuments of the Giza pyramid complex. He journeys on to explore the ruins at Abydos, Karnak and Luxor, arriving finally at the island of Philae, the site of the last hieroglyphics and a little-known shrine to Egypt's lost Gods.

The Greeks. Ancient Greece was the first major civilization to emerge in Europe. Its seat of power in Athens was crowned by the Acropolis, the famed city of the Gods. Kenneally explores the surviving remnants of this great civilization and its Gods, including the Parthenon, home to the goddess Athena and the most spectacular of the monuments of the Acropolis; Delphi, the "Vatican" of ancient Greece, where the god Apollo spoke through his Oracle; and the Greek colony of Paestum in southern Italy, site of a temple to Poseidon.

The Romans. The spectacular rise and fall of the Roman Empire fascinates us to this day, as evidenced by the success of films like Gladiator and the HBO series Rome. The Romans took their Gods from the Etruscans, on the ruins of whose civilization they built their own. Kenneally visits the Forum, the epicenter of Roman religion, and the Pantheon, sanctuary of the Roman gods. In Caerleon in Wales, he reveals how the Romans carried their religion to the farthest reaches of the empire. And at Ephesus in Turkey, he traces the rise of the Christian deity that would ultimately overthrow the Roman gods.

The Maya. There is a vast pantheon of gods worshiped by the Maya. Different areas had different gods, and some were more important in one area than in another. Each location would also have it's special patron god. There was probably some sense of competitiveness between locations, where they felt that their patron god was stronger or more beneficent that others.

The Celts. The Celts believed in benign spirits and demonic forces, but made no churches or temples: nature itself was their cathedral. Kenneally visits ancient Celtic settlements in Austria, Italy and Greece. He explores the settlement of Castell Henllys in Wales, where the religion of the druids was broken by Roman military might. And at Newgrange, Ferrycarraig and Dun Aengus in Ireland, he reveals how the Celts came to adopt the Gods of those who had preceded them.