Entrance to the complex is paid at the ticket office opposite the museums. If you go on your own, start your visit in the museums to get a basic understanding of the history, then head to the ruins.
Scattered around the Tiwanaku site, you’ll find heaps of jumbled basalt and sandstone slabs weighing as much as 25 tons each. Oddly enough, the nearest quarries that could have produced the basalt megaliths are on the Copacabana peninsula, 40km away beyond the lake. Even the sandstone blocks had to be transported from a site more than 5km away. It’s no wonder, then, that when the Spanish asked local Aymará how the buildings were constructed, they replied that it was done with the aid of the leader/deity Viracocha.