To create the long-awaited installation, the iconic triumphal arch on the Champs-Élysées was wrapped in 25,000 square metres of silvery fabric.
It is set to stay in place for 16 days.
Khan, who is aiming to make London "the greenest city in the world", said its Ultra Low Emission Zone, tree-planting initiatives and cycle lanes made the city "the envy of the world".
This year's London Design Festival also took place this week.
Among the highlights from the event was a virtual installation by architect Sou Fujimoto, created in collaboration with mixed reality studio Tin Drum, and a self-supporting pavilion made from simple aluminium sheets.
Over in the US, the Chicago Architecture Biennial kicked off this week.
The event's fourth edition has seen a roster of newly commissioned installations erected across the city, courtesy of studios including Atelier Bow-Wow and Manuel Herz Architects.
In design news, French designer Philippe Starck gave the traditional Venetian gondola a futuristic makeover.
Named Dream of Winter Gondola, Starck's modern interpretation of the watercraft was designed as a "symbol for the future of Venice".
We continued our series of Dezeen guides this week with a look a plastic.
The guide includes more than 11 types of plastic commonly used in architecture, design and interiors, with links to hundreds of projects for inspiration.
Our lookbook this week focused on apartments with adaptable and reconfigurable layouts.