30 St Mary Axe

Lonely Planet review

Known to one and all as 'the Gherkin' for obvious reasons when you see its incredible shape, 30 St Mary Axe - as it is officially and far more prosaically named - remains London's most distinctive skyscraper, dominating the city despite actually being slightly smaller than the neighbouring NatWest Tower. The phallic Gherkin's futuristic, sci-fi exterior has become an emblem of modern London as recognisable as Big Ben or the London Eye.

Built in 2002-03 to a multi-award-winning design from Norman Foster, this is London's first ecofriendly skyscraper: Foster laid out the offices so they spiral around internal 'sky gardens'. The windows (one of which popped out of its frame in 2005) can be opened and the gardens are used to reprocess stale air, so air-conditioning is kept to a minimum. Its primary fuel source is gas, low-energy lighting is used throughout the building and the design heightens the amount of natural light let into the building, meaning that less electricity is used.

Its 41 floors mainly house the reinsurance giant Swiss Re's London offices, and tours are not currently possible. The gorgeous top-floor restaurant is usually open only to staff and their guests, but it's possible to gain access by booking one of the private dining rooms, although this will need to be done well in advance. In some years mere mortals are granted access during the superb Open House Weekend (www.openhouse.org.uk), an annual September event. When included as a venue, the Gherkin is always one of the most popular openings.