The Guinigi Tower

**A soil basin built into the crown over a vault designed to carry it — deliberate engineering, not an accident.** ✅ **The structure**: the tower's top is not a flat roof **but a walled basin** holding **soil deep enough** for oak roots. **Beneath it is a stone vault** distributing the weight into the tower's walls — **the design accounts for the load of soil, water and trees together**, which is considerable. ✅ **Drainage is critical**: **if water were trapped, the soil would saturate, the weight would double and damp would penetrate the stone** — **so there is drainage** carrying the excess away. ✅ **And the species suits**: **holm oak (Quercus ilex)** is evergreen, **its roots are not aggressive** like poplar or fig, **and it tolerates shallow soil, wind and drought** — **exactly what a tower roof demands**. ⚠ **Maintenance is constant**: **the trees are pruned and the roots and basin monitored** continually, and the trees have been replaced over the centuries; **today's are not the 14th-century ones**, **but the tradition and the structure are original**. ✅ **The idea**: **roof gardens were a status symbol** in the tower cities of the Middle Ages — **a luxury saying its owner could afford to grow a garden in the sky**.