There’s something endlessly alluring about drawing a city in fastidious detail, from Stephen Wiltshire’s astoundingly accurate hand-drawn 360º panoramas to James Gulliver Hancock’s quest to draw every building in New York City to French autistic savant Gilles Trehin’s imaginary megacity. Now, from Italian artist Matteo Pericoli comes London Unfurled — a remarkable 37-foot-long accordion-format book, following in the footsteps of Pericoli’s celebrated Manhattan Unfurled.

Over the course of two weeks, Pericoli walked more than 60 miles, or 100 kilometers, and traveled 20 miles along the Thames from Hammersmith Bridge to the Millennium Dome and back again, taking some 6,100 photos, which he spent the following two years recreating in his obsessive pen-and-ink drawings. But what makes the project all the more unusual is its vantage point — it “unfurls” the complexity of London from the river that both divides it and seals it together, using the city’s north and south banks as gateways to its dozen boroughs, hundreds of buildings, countless landmarks like the Houses of Parliament, Tate Modern, Battersea Power Station, and Millennium Wheel, and 41 bridges.

Pericoli breaks down his epic journey by the numbers for Abitare:

Length of each of the two originals: 11.50 m
Height of the each of the two originals: 30 cm
Number of bridges
Total: 41 (of which, North: 21, South: 20)
Number of waves
Total: 3,262 (of which, North: 1,842, South: 1,420, i.e. bigger waves in the South drawing.)
Number of cranes
Total: 58 (of which, North: 29, South: 29 – amazing, same number!)
Number of buildings
Total: 1,343 (of which, North: 766, South: 577, Houses of Parliament: 823)
Approximate number of windows
Total (approx.): 27,180 (of which, North: 14,955, South: 12,225)
Approximate length walked along the river for the actual drawings (i.e. not grand total and without the zig-zags, and not counting that I also walked all the way to the London Barrier and beyond, both sides)
Total: 36.7 miles (of which, North: 17.5 miles, South: 19.2 miles)
Total number of photos taken: 6,100

This process drawing will give you an idea of Pericoli’s signature blend of a documentarian’s precision and an artist’s whimsy:

See him literally unfurl his sketch for the north side drawing, complete with rolling-paper sound:

London Unfurled also comes as an iPad app that lets you seamlessly scroll the entire drawing, find specific landmarks, flip from north to south, and zoom into Pericoli’s astonishing detail.