Sky Garden, City Garden Bar

Sky Garden crowns 20 Fenchurch Street, the building everyone in London still calls the Walkie Talkie, and it is one of the few genuinely free things to do at height in the city. Entry to the garden itself costs nothing, though a ticket booked in advance is required, and visitors pass through airport-style security before a fast lift delivers them to the top floors and 360 degree views over the City and beyond.

The gardens, designed by Gillespies, use drought-resistant Mediterranean and South African planting to keep the space green year round, and they wrap around a handful of food and drink options, including the City Garden Bar, the Fenchurch restaurant at the top end of the price scale, and the more casual Sky Pod bar for anyone who just wants a drink with a view. None of them are cheap, and the City Garden Bar in particular gets busy enough that a wait for service is common on a weekend evening.

It suits a first-time visitor to London wanting the skyline without paying for The Shard, a work drink with a genuine wow factor, or anyone killing an hour before dinner elsewhere. It does not suit anyone in a hurry, given the security queue and the popularity of advance booking slots.

Sky Garden earns its place on any London list purely because it is free and the view is real, not a marketing line. The bars are overpriced for what lands in the glass and service can be slow, but for the cost of nothing but a booking slot, it remains one of the better vantage points in the city.