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.