Walk Kathmandu's lanes and watch them appear
FOG hides the whole world map under fog and clears only the streets you physically walk. In Kathmandu the interesting part is not the roads, it is the lanes between them.
A medieval core with a modern city around it
The old city of Kathmandu is one of the densest pedestrian street patterns you will walk anywhere. Between Kathmandu Durbar Square, Asan and Indra Chowk, the lanes are narrow, brick-paved, unsigned and constantly branching, opening without warning into bahal, the enclosed courtyards that sit behind the street frontage. Many of these routes are barely wide enough for two people and a motorbike, and the layout owes nothing to any plan.
Around that core, the modern city spreads across the valley floor: Thamel, Lazimpat, Baluwatar, Patan to the south across the Bagmati, Bhaktapur further east. The Ring Road circles the whole thing. Out there the streets are wider, dustier and much less pleasant to walk, with heavy traffic and inconsistent pavement.
The valley itself sits at about 1,400 metres, ringed by hills. Inside the city the ground is mostly gentle, but the edges climb: Swayambhunath sits on its own hill west of the centre, and the walk up its steps is a proper stair climb.
A walk that clears real ground
Start in Thamel and walk south. Follow the lanes through Thahiti and Chhetrapati, then east into Asan Tole, which is the busiest market junction in the old city. From Asan take the ancient route south-west through Indra Chowk to Kathmandu Durbar Square. Come back north on a different set of lanes. Getting lost is expected and is more or less the point.
That circuit is maybe three kilometres of actual distance but it clears a genuinely dense block of map because the lanes are so tightly packed. Add a second day in Patan, where the streets around Patan Durbar Square are just as fine-grained and quieter, and a third climbing to Swayambhunath.
For a long linear route, walk the Bagmati or Bishnumati riverside where paths exist, or take the road out to Boudhanath and do the kora circuit around the stupa. The circuit itself draws a clean ring.
Why the fog is satisfying here, and where it fights back
The old city is one of the best fog-clearing environments there is. The lane density means a single hour of wandering paints a solid patch instead of a thread, and because the lanes are unnamed and unmapped in places, the fog map genuinely records something you could not get any other way. You will finish a walk and see a shape you did not expect.
The two problems are physical. First, the lanes are narrow and lined with three and four storey buildings, which is a small-scale canyon effect. Positioning can drift a lane or two over in the tightest sections. It is not severe, but on a map this fine-grained you will notice it.
Second, the modern city outside the core is a slog. Ring Road walking is dusty, loud and unrewarding, and the air quality in the dry season is poor enough that people wear masks. Your map will show a bright dense heart and much thinner coverage beyond it.
Seasons and practicalities
When to walk. October and November are the best months: clear, dry, mild, with the mountains sometimes visible from the valley rim. Spring is good too. The monsoon from June to September turns the lanes muddy and makes long walks miserable. Winter mornings are cold and often hazy.
Air. The dry-season dust and traffic pollution are real. Early mornings are noticeably cleaner.
Surfaces. Brick, stone, broken paving and open drains. Watch your feet more than your phone. FOG keeps revealing with the app closed and the screen off, so there is no reason to be looking at it while you walk.
No account, no sign-up, no cloud, no analytics, no ads. The map stays on your phone and you can export your own data.
Questions people actually ask
Will FOG record lanes that are not on the map?
Yes. It reveals fog based on where your phone physically goes, not on a road database, so unmapped alleys and courtyards clear like anything else.
Do treks outside the valley count?
Yes. FOG works anywhere on Earth, and trails clear the same way streets do. Walking out of the valley leaves a long line across otherwise blank map.
What does the paid version cost?
USD 5.99 once. It unlocks unlimited ranks, every character, and history import from Google Timeline exports and GPX files. No subscription.
Can I see how much of Kathmandu I have covered?
Yes. For any city you have walked, the app shows what percentage of it you have lit up.
Start with a dark map.
FOG is free to explore. No account, no subscription, and your map never leaves your phone.
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