When, Why, and Where the Great Wall of China Was Built

Two Millennia of Construction

When: 7th century BC – 17th century AD (main Ming Dynasty walls: 14th–17th c.).

Why: Defense against northern nomadic invasions; border control; trade regulation (Silk Road); symbol of unity.

Where: Northern China, across 15+ provinces/regions. Total length ~21,000 km (including all branches).

Key Phases

• Qin (3rd c. BC): First connected walls.
• Han (206 BC–220 AD): Extended westward.
• Ming (1368–1644): Built the iconic brick/stone sections (e.g., Badaling).

The Wall is history’s longest construction project.