The International Space Station wasn't launched in one go: it was assembled in orbit from 1998 onwards, piece by piece, over more than forty assembly flights. The first module was Zarya, built in Russia and paid for by NASA; two weeks later came Unity, the first US node. The last big additions were the Russian Nauka laboratory and the Prichal node, in 2021.
The model uses NASA's public 3D model and shows the best-known moves of parts during assembly; the plan is a diagram with approximate positions. Agency colors show who runs each module, not its real color, which is almost always white or silver. Visiting spacecraft such as Crew Dragon, Soyuz or Progress are left out because they change every few weeks; you can follow them under Launches.
How to explore the station inside
Press "Go inside" to step into the interior. On a computer, move with W A S D or the arrow keys, go up and down with E and Q, and look around by dragging with the mouse; on a phone you get an on-screen stick and buttons to go up and down. Hatches between modules open with the F key or a tap. Some modules have windows that look out on the Earth: try the ones in Zvezda, Zarya, Poisk and Nauka on the Russian segment, the floor window in Destiny and, above all, the Cupola. The minimap shows which module you're in and which way you're facing, and the "Go to" menu takes you straight to any other.
The interiors of Unity, Destiny, Harmony, Tranquility, the Cupola, Kibo and Columbus come from models published by NASA; the rest are approximate recreations.
Two segments, five agencies
The station has two halves that work almost like two stations joined together. The Russian segment, controlled from Moscow, includes Zvezda, with engines to adjust the orbit, and the docking modules for Soyuz and Progress. The US segment, controlled from Houston, brings together the laboratories of NASA, Europe (Columbus) and Japan (Kibo), plus the Canadian robotic arm. The two halves meet at a single point: the passage between Zarya and Unity, through the PMA-1 adapter.
You'll spot it straight away in the model's colors: each one shows the agency that manages the module. To get a sense of size, the main truss, which carries the solar arrays, is 109 meters (358 feet) long, about the length of a football field, and the pressurized space is like that of a large house, split into tubes just over four meters (13 feet) across at most: that's what fit in the Space Shuttle's payload bay or under a rocket's fairing.