30 St Mary Axe, the 41-story London tower everyone calls the Gherkin, grew out of a crater. In April 1992 a Provisional IRA bomb wrecked the Baltic Exchange, the historic heart of global shipping trade, along with the Chamber of Shipping at 24 to 28 St Mary Axe. English Heritage and the City of London Corporation first demanded the old facade be restored, but the damage was too severe, and the salvaged pieces were sold for 800,000 pounds and shipped to Tallinn, Estonia. Planners relaxed their rules on one condition: the replacement had to be architecturally significant. A 386 meter London Millennium Tower proposed in 1996 was dropped because it would have cut into flight paths for Heathrow and London City airports, and Foster + Partners won the job in 1999.

The result was a passive environmental machine: six spiraling light wells that pull warm air up and out in summer and trap solar heat in winter, cutting energy use by up to 50 percent, all wrapped in an Arup diagrid that resists wind sway without a pendulum damper. It won a unanimous Stirling Prize in 2004. Then reality arrived. In April 2005 a glass panel fell to the plaza, forcing checks on more than 700 others, and security-minded tenants such as Swiss Re put up glass partitions that choked the airflow the design depended on. Swiss Re sold the building in 2007 for 630 million pounds, the new owners went into receivership in 2014 over multi-currency loans, and the Safra Group bought it for 700 million pounds.

• Why the tower that looks perfectly round contains only one curved pane of glass, the lens-shaped cap at the top
• The hydraulic lift that pushes up from below so no machinery blocks the glass dome over the 40th floor bar
• Ken Shuttleworth’s 2011 admission that the team would approach the all-glass design differently today
• How a pound-versus-foreign-currency swing pushed a fully leased landmark into receivership
• The 1,600-year-old skeleton of a Roman teenage girl found during construction and reburied at the tower’s base in 2006