Twenty-four cities, each showing its own local time, all derived from the same instant. The trick is that nothing here is stored — every hand is computed from the browser's clock and the city's offset, so the wall stays correct wherever you open it.
Every clock on this wall is wrong, and the one in the top right is no more wrong than the one below it. A time zone is a political instrument — an agreement about what hour it is when the sun is where it is — and the moment the agreement changes, somebody's midnight becomes somebody's 11 p.m.
The city that changes most often is the one furthest east. When the prime meridian jumps a day, Kiribati is briefly a whole calendar year ahead of anyone else, which is why the line eventually had to be moved.