Hillfort, Nasielsk
Narodowy Instytut Dziedzictwa pl

The earthwork in Nasielsk is an example of a lowland ring fort. As a remnant of early medieval fortifications, it is a valuable archaeological find.

Location and description

The ring fort, which is known as the ‘Mound’, is located in the north-eastern part of the city. It is surrounded by marshy meadows in the Nasielna river valley, on its right bank.

The ‘Mound’ is a ring fort. The site is a flat raised area of land which is around 2 metres in height and around 80 metres in diameter. The maidan, which is the inner part of the ring fort, is approx. 30 metres in diameter. The area of the ring fort is now a wasteland.


The name ‘Nasilzco’ occurs for the first time in the so-called Mogilno Falsification of 1155 It was a prince’s document allegedly issued in 1065 that specified new properties acquired by a Benedictine Abbey located in Mogilno. The town was also mentioned in the Bolesław IV the Curly’s document of 1155 but under the name ‘Nasidlzk’. In 1257, Siemowit, Duke of Masovia, granted the third part of Niesielsk to the Abbey church in Czerwińsk.

The findings made during an archaeological investigation indicate that the ring fort is a multi-phase structure dating back to the 2nd half of the 9th century - 2nd half of the 13th century.

Condition and results of archaeological research

The first surface surveys of the ring fort were carried out in 1951. Surveys under the supervision of I. Górska were made in 1967. Between 2001 and 2006 the ring was investigated by M. Błoński from the Institute of Archeology and Ethnology of the Polish Academy of Sciences. In 1998, the ring fort was registered during the surface surveys carried out within the framework of the “Archaeological Picture of Poland” project.

In 1967, excavations were opened in the central part of the maidan and in the southern part, on a rampart. Excavations of the site uncovered a fragment of a rampart built of stone and earth and a part of a moat. The cultural layer, which is a layer of soil formed during the functioning of the fortified settlement, on the maidan was over one metre thick. The archaeological investigations revealed numerous fragments of ceramic vessels, iron knifes, ring of bronze plate, bone awl, clay spindle whorl, among others. The presence of iron slag indicated that iron smelting has been carried out on the site.

Due to the level of groundwater, the oldest section of the ring fort was not subject to an archaeological investigation. These deficiencies were remedied during the latest investigations. Between 2001 and 2006, archaeologists investigated a fragment of the access road to the fort gate and uncovered a part of the maidan. Based on the carbon-14 dating, among others, researchers found that the area adjacent to the ring fort was inhabited as early as the 7th century. Fragments of ceramics dating back to the period preceding the establishment of the fortified settlement were found in the rampart from the first phase and in the levelling layers preceding its construction. The remains of the oldest 2.5-metre-wide rampart were uncovered near the maidan of the ring fort. These included a starling, which was a box filled with stones and sand and covered with a sandwich construction. The latter was built of oak logs which were 15 cm in diameter, arranged longitudinally and transversely to the line of the rampart, with sand in-between the layers of logs. The ring fort from the first phase was 35 metres in diameter. The fortified settlement from the first phase, which was established in the 860s, was destroyed a dozen or so years after it was built, as indicated by a small thickness of the usable layer from that period and a small number of monuments (several fragments of ceramics compared to several thousands of fragments dating back to the later phases). The fortified settlement was destroyed by fire probably as a result of a power struggle over the territory adjacent to it.

The hill fort is located in the area of land being private property, approx. 200 m to the south of an unpaved road (Brzozowa Street).

Compiled by Agnieszka Oniszczuk, National Heritage Board of Poland, 19.08.2015 r.


  • Błoński M., Dendrochronologia o początkach grodu w Nasielsku, [in:] Krasna-Korycińska M., Żurek M. (ed.), Grody wczesnośredniowiecznego Mazowsza. Archaeologica Hereditas 4, in print, Warsaw 2015, pp. 223-228.
  • Błoński M., Szwarczewski P., Antropogeniczne przekształcenia doliny Nasielnej w sąsiedztwie wczesnośredniowiecznego grodziska w Nasielsku, ,,Archeologia Polski” 2008, vol. 53, issue 2, pp. 291-316.
  • Błoński M., Szwarczewski P., Zapis działalności człowieka w osadach wypełniających dno doliny Nasielnej w Nasielsku, „Landform Analysis” 2008, Vol. 9, pp. 272-275.
  • Gajewski L., Górska I., Paderewska L., Pyrgała J., Szymański W., Badania sondażowe grodzisk Mazowsza i Podlasia w latach 1966 - 1968, „Sprawozdania Archeologiczne“ 1970, vol. 22, pp. 159-160.
  • Górska I., Nasielsk, pow. Pułtusk, „Informator Archeologiczny”, Badania rok 1967, 1968, pp. 246-247.
  • Górska I., L., Nasielsk, gmina loco (d. pow. Pułtusk), woj. ciechanowskie, [in:] Grodziska Mazowsza i Podlasia (w granicach dawnego województwa warszawskiego), collective work, Wrocław -Warszawa -Kraków -Gdańsk, 1976, pp. 83-85.
  • Słownik geograficzny Królestwa Polskiego i innych krajów słowiańskich. T. 6, Warsaw 1880-1914, pp. 924-925, http://dir.icm.edu.pl/pl/Slownik_geograficzny/Tom_VI [access: 26.06.2015]

General information

  • Type: hillfort
  • Chronology: 2 poł IX – 2 poł. XIII w.
  • Form of protection: register of monuments
  • Address: Nasielsk
  • Location: Voivodeship mazowieckie, district nowodworski, commune Nasielsk - miasto
  • Source: National Heritage Board of Poland


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