Sky Garden, 20 Fenchurch Street

20 Fenchurch Street stands in the City of London on the site of a 25-storey, 91 m building completed in 1968 for Land Securities to designs by William H. Rogers and demolished in 2008. In 2004 Land Securities and Canary Wharf Group commissioned the new tower from the Uruguayan architect Rafael Viñoly. First proposed at nearly 200 m, it was lowered after heritage objections, approved in 2006 and confirmed in 2007 when a public inquiry found in the developers' favour; the public garden planned for the top was among the arguments that justified consent.

Piling began in January 2009, the steel frame topped out in December 2012 and the building was completed in August 2014, the first tenants having moved in during May. The summer of 2013 exposed a famous flaw: the façade reflected sunlight onto the street with enough intensity to damage parked cars, earning the tower the nicknames 'Walkie-Scorchie' and 'Fryscraper'; a permanent awning was fitted in 2014.

The Sky Garden opened in January 2015. That same year the tower won the Carbuncle Cup for Britain's worst building, and critics found the garden, planted with ferns and succulents rather than the full-height trees of the early visualisations and subject to strict access rules, short of what had been promised. In July 2017 the Lee Kum Kee group bought the tower for £1.3 billion. The terrace is named after Francis Golding, a former secretary of the Royal Fine Art Commission, involved with the project from 2005, who had supported it at the 2007 inquiry and died in November 2013.

Viñoly's tower inverts the usual volume of a skyscraper: the footprint at ground level is reduced and the floorplates grow larger as they rise, freeing public space at the foot and at the top of the building and giving it its nickname. Its curved profile, 160 m high, completes, in the practice's words, the arc formed by the Eastern Cluster towers towards the Thames. Wikipedia counts 37 floors topped by the three-level garden; the practice speaks of 32 office levels and a gross area of 104,520 m². Adamson Associates was executive architect and Halcrow Yolles structural engineer.

The garden begins at level 35, beneath what Designboom describes as a large glass dome. The tower's structural fins, 1.2 m deep, span the open terrace to form a large portal frame and carry the glazing over the top and sides of the enclosure. On the north façade the upper-floor curtain wall runs up to the louvres of the arched roof, forming a tall urban window the full height of the garden; vertical louvres shade the east and west elevations, while the south side is ventilated externally. The bars and gardens are naturally ventilated, at outdoor temperatures, and only the two restaurants are heated; the open-air Fenchurch Terrace looks out over the city. Two express lifts serve the garden. The building, rated BREEAM Excellent, draws 300 kW from a fuel-cell tri-generation plant and received a commendation in the 2015 Structural Steel Design Awards.

Designed by the landscape practice Gillespies and installed by idverde, the planting favours, according to the official site, drought-resistant Mediterranean and South African species chosen to thrive all year under the glass: African lily (Agapanthus), red hot poker (Kniphofia), bird of paradise (Strelitzia reginae) and, among the herbs, French lavender. Wikipedia describes the whole as a slope planted with ferns and succulents, climbing the three levels between the viewing platforms.

The tower's owner has partnered with the horticultural charity Thrive. Critics cited by Wikipedia found the vegetation sparser than the early visualisations had led people to expect. At the foot of the tower, Gillespies also designed planted plazas and a small pocket park linking Rood Lane and Philpot Lane.

The entrance to the Sky Garden is at the south-west corner of the tower on Philpot Lane, in the heart of the City. Entry is free but must be booked: tickets are released every Monday for the three weeks ahead and allow one hour on site; diners at the two restaurants need no ticket, and groups of more than ten are admitted only on community days. The route is step-free. The open-air terrace may be closed without notice in bad weather, and the bars and gardens are at outdoor temperatures. About 1.3 km to the north, the Barbican Conservatory, another glazed garden of 1984, rounds off a day devoted to the capital's glasshouses.