There is not much that can be said about Thirty, given the fact that most of it remains underground. Geophysical survey suggests, however, that Structure Thirty is another very large piered building on the same NNE-SSW alignment as Structure Twelve.
The curvature of its exposed wall also suggests Thirty was larger than its north-western neighbour.
Excavation in 2023 confirmed that Structure Thirty was built after Twelve.
The building sits higher than Twelve and its northern end appears to have been set back to avoid blocking the view from Structure Twelve’s eastern entrance.