Whether you are religious or not, it must be accepted that religion has been with us for a very long time. Some of the most monumental structures ever made have had religious functions. Today it is still possible to be moved by the ruins of these sites, even though the people who made them, and sometimes the gods they were raised to, have disappeared.
Borobudur: Indonesia
Delphi: Greece
Pyramids of Teotihuacan: Mexico
The Ziggurat of Ur: Iraq
Callanish Stones: UK
The Karnak Temple Complex: Egypt
Gobekli Tepe: Turkey
The Hypogeum: Malta
The Pantheon: Rome
The Ajanta Caves: India
Borobudur: Indonesia
Delphi: Greece
Pyramids of Teotihuacan: Mexico
The Ziggurat of Ur: Iraq
Callanish Stones: UK
The Karnak Temple Complex: Egypt
Gobekli Tepe: Turkey
The Hypogeum: Malta
The Pantheon: Rome
The Ajanta Caves: India