LT2004 m. Biržų senamiesčio (A 518) penkiose vietose vykdyti archeologiniai tyrimai, kurių metu surinkti radiniai perduoti BKMS [p. 193].
ENIn 2004 in the old town of Biržai archaeological investigations were performed at 5 sites. At the Reformatų Str. 3 the total area of 30 m2 was investigated; a crypt and an ancient church foundation were discovered. At the Rotušės Str. an area of about 7.5 m2 was investigated and a building foundation was found. At the J. Basanavičiaus Str. 1 and at the Vytauto and J. Basanavičiaus Str. an area of 30 m2 was investigated; a stone pavement of the first half of the 17th century, a road, fragments of stove-tiles and coins were discovered. In the path of a power cable trench at the J. Janonio Square and the Vytauto and J. Basanavičiaus Str. an area of about 200 m2 was investigated; fragments of building foundations were found.