The correct answer to this open question is the following.
As there is no text attached to this question, we can say that the remarkable achievement of the Mayan architecture is the building called "El Mirador."
Tne meaning of "El Mirador" is something like "the viewpoint." This impressive building has an architectonic design that has impressed archeologists since it was discovered in the 1960s. "El Mirador is located in Petén, the north region of Guatemala, where archeologists have found many Mayan ruins.