Þingvellir is 49km (30 miles) NE of Reykjavík; Geysir is 118km (73 miles) NE of Reykjavík; Gullfoss is 125km (78 miles) NE of Reykjavík.
The "Golden Circle" route isn't notably golden or circular, but whatever the marketing term, it still would have become the most popular day tour in Iceland. Each Golden Circle tour has its minor variations, but all include three major sights: þingvellir, meaning "Parliament Fields," where the Icelandic parliament first convened in 930; Geysir, a geothermal hotspot for which all geysers are named; and Gullfoss, a majestic waterfall. Nearby sights are often incorporated into the route, particularly the Nesjavellir power plant, Kerið crater, and Skálholt, once the most dominant settlement in south Iceland. The Golden Circle is often called "requisite," a "must-see," or "the day tour."