CN Tower’s Center of Gravity: Not a Published Spec, But Calculable

The CN Tower (Toronto, 553.3 m) doesn’t publish its center of gravity (CoG)—but structural engineers can describe it:

What Determines It

• Mass distribution: 117,000 tonnes total. Core (concrete): 60% mass, centered. Pod (observation, restaurant): 350 m up. Antenna: 102 m steel mast (top 100 m).
• Foundation: 7,000 m³ concrete, 6 m thick, 15 m deep — anchors CoG low.

Estimated CoG

~60–70 m above grade (roughly at the base of the main pod / SkyPod level). The massive concrete shaft dominates; the antenna adds height but little mass.

Why It Matters

• Stability: CoG well within base footprint (diameter 15 m at grade). Overturning moment from wind (100-yr gust 140 km/h) + seismic = FS > 2.0.
• Dynamic response: CoG height affects natural period (~7 sec sway). Tuned mass damper (donut at 300 m) counters motion.
• Construction: Slipforming required CoG tracking daily.

Public Data

No official CoG coordinate released (proprietary/engineering). Structural drawings (John Andrews Architects, WZMH, Foundation Building Design) held by Canada Lands Company. Researchers request via NRC/CN Tower archives.

For a 553 m tower, CoG at ~65 m is remarkably low — testament to the "concrete spike" design.