Ephesians 3:18 may allude to the Temple of Artemis in Ephesus, one of the Eight Wonders of the Ancient World, which was roughly four times the size of the Parthenon of Athens and boasted the largest interior space of any building in the ancient world.
Enterprises and wealthy individuals from across the Mediterranean world stored their wealth there where it was protected by the vengeful wrath of the goddess Artemis while accruing interest from loans made by temple officials, such that the temple treasury functioned as the largest banking institution of the Eastern Mediterranean in Paul's day.
Travelers who had seen the Pyramids of Egypt, the Lighthouse of Alexandria, and the Colossus of Rhodes were more impressed with the Temple of Artemis in Ephesus; but the glory of our riches in Christ greatly exceeds those of this now bygone temple, and precisely that implication is likely what provoked the riot that forced Paul to leave the city (Acts 19:23-31).
