Classic features indicate links with Chichen Itza, in the northern Yucatán Peninsula, or with Tula in central Mexico. The population of Tazumal coexisted with the Nahua-speaking Pipils from the Classic through to the Early Postclassic until at least AD 1200. The Pipil influence may have been due to trade with neighbouring Pipil populations rather than a direct Pipil presence, judging by the level of evidence. After 1200, Tazumal was largely abandoned, with occupation shifting westwards towards the centre of what is now the modern town of Chalchuapa. Chalchuapa was still occupied at the time of the Spanish conquest, at which time its inhabitants were Poqomam Maya. The Pokomam are believed to have been relatively late settlers in Chalchuapa, postdating the Pipil influence that lasted until 1200. Between 1942 and 1944 Stanley Boggs excavated and restored structures B1-1 and B1-2. This restoration included coating the structures with modern cement, which Boggs judged to be sufficiently similar to their original appearance as to justify its use. Boggs' final report was not made generally available and no further archaeological investigations were carried out until the early 21st century. In 1947 Tazumal was declared a National Historic Monument. Until 2001, the Salvadoran 100 colón note carried an illustration of the ruins of Tazumal. In 2004, the side of Structure B1-2 collapsed and the Salvadoran Consejo Nacional para la Cultura y el Arte (CONCULTURA - National Council for Culture and Art) initiated operations to excavate and stabilise the ruins. During the first decade of the 21st century, two simultaneous archaeological projects were initiated, the investigation of Structure B1-2 by CONCULTURA and the Proyecto Arqueológico de El Salvador (PAES) by the Japanese University of Nagoya. Site description All the buildings in the Tazumal complex face west. Tazumal is believed to possess a Mesoamerican ballcourt; this is based upon the external appearance of two unexcavated mounds that are situated in the northwestern portion of the site, within a 20th-century cemetery. One of the mounds is badly damaged. Green obsidian artefacts found at Tazumal indicate links with central Mexico. Structure B1-1 Structure B1-1 is the principal structure in the Tazumal group and dominates the complex. The pyramid underwent various phases of construction through the Classic and Early Postclassic periods. Structure B1-1 was built upon a basal platform, called the Great Platform by Boggs, that measures (east-west by north-south). The pyramid was surveyed in 2003–2004. A long platform runs