LT2021 m. Biržų senojo miesto vietoje (UK 3219), istorinėje miesto dalyje (UK 17073), J. Bielinio ir Reformatų gatvėse vykdyti tęstiniai tyrimai, pradėti 2019 m. (ATL 2019 metais, 2020, p. 216–216). 2021 m. atlikti detalieji tyrimai, kurių metu ištirtos 7 perkasos (390 m2 bendro ploto) bei atlikti žvalgymai 8000 m2 plote. Rasti ir į BKMS perduoti 2275 archeologiniai radiniai. Detaliųjų tyrimų metu perkasoje 1, ties ŠR perkasos dalimi 25 cm gylyje fiksuotas XX a. I pusėje naudoto rūsio (pusrūsio?) fragmentas, kurio tęsinys atidengtas žvalgymų metu. Perkasoje 70–90 cm gylyje atidengti supuvusių spygliuočio medienos rąstų fragmentai. PV pusėje buvęs rąstas apie 4,1 m ilgio, o ŠR pusėje apie 1,7 m. Rąstai apie 15–20 cm skersmens. Visa atidengta struktūra buvo apie 4,3 m ilgio R–V kryptimis bei apie 4,4 m pločio Š–P kryptimis. Pagal supiltiniame grunte rastus XX a. II pusės radinius galime teigti, jog šis buvęs rūsys (pusrūsis) užverstas po II Pasaulinio karo, veikiausiai prieš įrengiant miesto estradą. [...] [p. 278].
ENThe 2021 investigation (7 trenches totalling 390 m2 and a roughly 8000 m2 survey) on J. Bielinio and Reformatų Streets in Biržai (N Lithuania) yielded 2275 archaeological finds. Trench 1 revealed a late 16th – early 17th-century, 6.5x5 m cellar filled with stones and mixed soil containing late 16th–17th-century finds (stove tile and household pottery sherds), the former floor level being reached at a depth of 1.75–1.8 m, as well as part (6.6x2.4 m) of a second filled-in masonry cellar fragment dating to the first half of the 17th century. At a depth of 2 m, a jar base was discovered in situ at the bottom of the cellar, the former floor level, and a Christina Riga shilling in the fill. It appears that the cellar could have been filled in after the Great Fire of 1666. At a depth of 40–50 cm, Trench 2 yielded a fragment of a 5.9x2.2 m cellar made from limestone and filled with limestone mixed with soil containing stove tile sherds dating to the late 17th – first half of the 18th-century and up to the early 19th century, sherds of household pottery, and glass bottle shards. Based on these finds, the cellar was dated to the first half of the 18th – early 19th centuries. At a depth of 1.25–1.8 m, Trench 4 revealed a 2.1x1.8 m domed stove made of fieldstones and red bricks with frogs. The pit near the stove was turned into a storage pit once the stove stopped being used. A roughly 9.2 m long foundation fragment was uncovered on the S side of the stove. Based on the discovered finds, the stove was dated to the second half of the 16th century, the foundation fragment to the late 16th – early 17th century.