most (not all, some contributions are QTVR-only due to historical reasons)
Javascript + HTML5 / WebGL
many, but depends on photographer's choice of file upload (newer event = more likely to work) and your device's capabilities. You may experience slow playback, distorted images or unexpected browser quitting if there is only limited memory/GPU power available.
Trains meet under the bridge in Tornakalns, one of the green regions situated on the left bank of Riga, Latvia. Now a relatively unhurried neighborhood, the future urban development plans foresee construction of new municipal and academic campuses around this place. But so far - just the sound of trains rushing south and west, and seldom passers-by crossing the bridge over the railroad...