Walk Prague and lift the fog lane by lane
FOG covers the world map and clears it only along streets you have physically walked. Prague is a medieval knot wrapped in nineteenth century blocks, which makes for two very different kinds of filling in.
Prague on the FOG map, fog burned off along a walked route through the old town and over the river.
A knot in the middle, blocks around it
Stare Mesto was never planned. The lanes curve, fork and rejoin, and there are stretches where you can walk five minutes and end up forty metres from where you started. Old Town Square is the anchor, Josefov sits north of it with the old Jewish quarter, and Wenceslas Square is not a square at all but a long sloping boulevard running up to the museum.
Across the Vltava, Mala Strana is quieter and steeper, climbing toward Hradcany and the castle. Petrin hill rises behind it with a funicular and a set of paths through orchards. Vysehrad sits on its own rock downstream.
Beyond the tourist ring the city changes character completely. Vinohrady is orderly apartment blocks around Namesti Miru. Zizkov is hilly, scruffier and more interesting. Karlin is flat and rebuilt, Holesovice is warehouses turning into galleries, Smichov is on the far bank. Those outer districts are where most of the actual walking is.
An afternoon along the river
Start at Vysehrad, walk the ramparts for the view down the valley, then come off the rock and head north along the embankment. The naplavka riverside path runs at water level below the road, which keeps you out of traffic for a good stretch.
Carry on past the National Theatre, cross to Kampa island and wander the small streets behind it, then climb through Mala Strana toward the castle. Come back down the old castle steps and return across Charles Bridge. The bridge is unbearable at midday and quite different at seven in the morning, so choose your hour.
That loop is around eight kilometres and it lights up both banks plus the castle hill. If you want more, add Letna park above Holesovice, where the plateau gives you the whole river and its bridges lined up at once.
How the fog behaves here
Two different games. In the old town the lane density is enormous, so a slow hour of deliberately turning down every gap clears a large share of a small area and it feels great. You will also find yourself walking the same passage twice without realising, because the geometry lies to you.
Out in Vinohrady or Zizkov it is ordinary block walking, steady and predictable, and that is where city percent actually moves, because those districts are far bigger than the historic core.
Practical notes. The old town lanes are narrow with tall buildings on both sides, which is the classic case for a GPS line drifting a few metres before it settles. Everything is cobbled, so shoes matter more than usual. Winter is properly cold and the January dark comes early, though the city is at its best in a hard frost with nobody on Charles Bridge. Spring and autumn are the comfortable seasons.
What the app does
The whole map begins hidden. You reveal streets by physically walking, running or riding them, and revealed streets stay revealed for good.
There is no account, no sign-up, no cloud, no analytics, no ads and no tracking. The map never leaves your phone and you can export your data. Background exploring keeps revealing with the app closed and the screen off, so you are not draining the battery to record a day of walking.
Exploring is free. One purchase of USD 5.99, and never a subscription, unlocks unlimited ranks, every character and history import from Google Timeline exports and GPX files. Ranks climb with area covered: Wanderer, Scout, Pathfinder, Explorer, Voyager. The collection covers 241 countries, 3,390 regions and 7,342 named places, collected only by physically standing in them. For any city you have walked, FOG shows what percentage of it you have lit up.
Questions people actually ask
Is the old town hard to fill in completely?
It is dense rather than large. The lanes fork and rejoin, so you cover ground quickly but you will also retrace yourself without noticing. A patient morning clears a lot of it.
Where does city percent actually move?
In the outer districts. Vinohrady, Zizkov, Karlin and Holesovice are much larger than the historic core, so ordinary block walking there moves the number faster.
Do the narrow streets affect GPS?
In tight lanes with tall buildings on both sides the line can drift a few metres before it settles. That is a limitation of satellite positioning anywhere, not of Prague specifically.
Can I add walks I did here before installing?
Yes, with the paid unlock. FOG imports Google Timeline exports and GPX files.
Start with a dark map.
FOG is free to explore. No account, no subscription, and your map never leaves your phone.
free to explore · one purchase unlocks everything · never a subscription