This is a sponsored article on behalf of the Art Fund.
We're all about the whole of London — there's masses of cultural stuff to discover outside zone 1, and best of all, you can get reduced price entry to a bunch of these outer London treasures with a National Art Pass.
Flex those travelcards and visit the gems outside zone 1 — to infinity and beyond.
1. Marble Hill House
Step back in time to fashionable 18th century London at this exquisitely restored palladian pile.
Intended as a riverside retreat for George II's mistress, the villa is set amid 66 acres of arcadian gardens and houses a fine collection of paintings from the period. Fortunately nowadays you don't have to be dallying with a royal to enjoy this leafy escape from the hustle and bustle of zone 1.
Marble Hill House: Richmond Road, Twickenham, TW1 2NL.
Standard admission is £6.60, free with the National Art Pass.
2. Dulwich Picture Gallery
The first purpose-built art gallery in Britain, we rated this south London stalwart one of our Londonist picks of 2015 — and one step inside Sir John Soane's architectural masterpiece makes it easy to see why.
Consistently punching above its weight, Dulwich Picture Gallery boasts temporary exhibitions to rival the big boys of zone 1 (the current offering is the critically-acclaimed Nikolai Astrup: Painting Norway) and a permanent collection of priceless European old masters and renowned works by Reynolds, Gainsborough, Rubens, Claude, Van Dyck, Poussin and Rembrandt.
Dulwich Picture Gallery: Gallery Road, Dulwich, SE21 7AD.
Standard admission to the permanent collection is £5, free with the National Art Pass. Standard admission to Nikolai Astrup: Painting Norway is £11, £5.50 with the National Art Pass.
3. Red House
A bricks-and-mortar manifestation of the arts and crafts movement, Red House is the only building to have been commissioned, created and lived in by William Morris.
As if that weren't enough to pique your interest, it's not just Morris who had a hand in this unique place: wall paintings have recently been discovered by Dante Gabriel Rossetti, Elizabeth Siddal, Edward Burne-Jones and Ford Madox Brown.
Burne-Jones, who also did the stained glass windows, described the house as "the beautifullest place on earth" and we can certainly see where he was coming from.
Red House: Red House Lane, Bexleyheath, DA6 8JF.
Standard admission to house and garden is £7.20 and to garden only is £2, free with the National Art Pass.
4. 2 Willow Road
Venture north to a quiet Hampstead street and discover the groundbreaking 2 Willow Road, one of the most interesting and influential examples of modernist architecture in London.
Designed by Ernö Goldfinger in 1939, the house is full of innovative design details, original pieces of furniture and unusual fittings that were way ahead of their time and still feel cutting-edge today.
The place also houses an important collection of 20th century artworks by big names like Henry Moore, Max Ernst and Bridget Riley.
2 Willow Road: 2 Willow Road, Hampstead, NW3 1TH.
Standard admission is £6.50, free with the National Art Pass.
5. Estorick Collection of Modern Italian Art
This may border zone 1 (we're placing it in the spiritual world of zone 2) but on our regular visits, we often find we have the collection almost to ourselves.
This serene Grade II-listed townhouse, chock-full of priceless works from 20th century Italy, is an absolute must-see both for anyone interested in modern art, and for those who think Italian art peaked in the Renaissance.
Fascinating temporary exhibitions shed further light on under-appreciated artists and intriguing modernist movements. There's also a tempting courtyard café — perfect to mull over your thoughts on Modigliani and Morandi over an Italian-style espresso.
Estorick Collection of Modern Italian Art: 39a Canonbury Square, Islington, N1 2AN.
Standard admission is £5, £2.50 with the National Art Pass.
6. Leighton House Museum
This Holland Park concoction is the fantastical result of limitless imagination.
The aesthete Frederic Lord Leighton created this "private palace of art" as both home and studio; now it's a glorious homage to his unbridled mind and eccentric collecting, and one we can all enjoy.
The two-storey Arab Hall houses over 1,000 Middle Eastern tiles, the Silk Room boasts fine examples from Millais, Burne-Jones, Watts and Sargent, and Leighton's vast domed studio evokes sophisticated soirées of the building's past.
Leighton House Museum: 12 Holland Park Road, Kensington, W14 8LZ.
Standard admission is £10, £5 with the National Art Pass.
7. Ranger's House
This imposing red brick mansion in Greenwich Park has a glittering royal history and even more sparkling exhibitions.
Assembled by diamond magnate Sir Julius Wernher, the 700-strong collection sparkles with Byzantine decorative art, renaissance bronzes, gothic ivories, sumptuous medieval silverware, modern marbles and fine art by the likes of Sir Joshua Reynolds and the Dutch old masters.
Ranger's House: Chesterfield Walk, Blackheath, SE10 8QX.
Standard admission is £7.60, free with the National Art Pass.
8. Royal Observatory
We're a little bit obsessed with Greenwich, and for good reason: the place is simply teeming with royal, scientific and historical magnificence.
The Royal Observatory is the apotheosis of Greenwich's glories: founded by Charles II in 1675, the observatory is home to London's only planetarium and Greenwich Mean Time, the world's Prime Meridian Line from which all other places are measured.
Prepare to have your mind blown at the observatory galleries which explore the extraordinary phenomena of time, and unravel the mysteries of space through a world-class collection of paintings, clocks and other astronomical instruments.
Royal Observatory: Blackheath Avenue, Greenwich, SE10 8XJ.
Standard admission is £9.50, £4.75 with the National Art Pass.