Alsnö hus
Ruins Ruins of a medieval royal palace on Adelsö
Ruined medieval royal manor on Adelsö in Lake Mälaren, associated with 13th-century assemblies; visitors explore exposed stone foundations, lakeside views and local historic exhibits.
Alsnö hus is the stone-ruin remains of a medieval royal manor on the island of Adelsö in Lake Mälaren, Stockholm County, Sweden. The complex dates to the late 13th century and is linked to important medieval state decisions.
Ruins include visible foundation walls and remnants of a hall complex that visitors can walk around on marked paths. The site is visited together with the nearby archaeological area of Hovgården and the Viking-age trading town of Birka, both within a few kilometres.
The manor was established in the late 13th century and is traditionally associated with royal authority in the Mälaren basin; it is the locality connected with the 1279 Ordinance of Alsnö. The building fell into disuse in later medieval centuries and survives today as an archaeological ruin.
The ruin sits on Adelsö island in Ekerö Municipality in Lake Mälaren, about 40 km west of central Stockholm. The landscape is lake-dotted and low-lying; visitor access is typically by road and local ferries or from nearby ports.
- UNESCO listing: The site is part of the Birka and Hovgården area that is listed as a UNESCO World Heritage Site (inscribed 1993).
- 1279 ordinance: The ruin is associated with the 1279 Ordinance of Alsnö, a key legal act that shaped medieval Swedish nobility.
How to Get to Alsnö hus #
Adelsö is reached by ferry from the Ekerö mainland (Bromma/Stockholm region access). From Stockholm, drive or take regional transit to Ekerö and connect to the ferry; local signage and heritage boards provide directions on arrival.
Tips for Visiting Alsnö hus #
- Combine a visit with a ferry to Adelsö island to explore other Viking-era sites and lake views.
- Check local signage for archaeological protections - parts of the site may be restricted to protect fragile remains.
- Wear sturdy shoes; the terrain around the ruins can be uneven and grassy.
Best Time to Visit Alsnö hus #
Best visited in summer for easy ferry connections and comfortable walking weather; shoulder seasons offer fewer crowds.
Weather & Climate near Alsnö hus #
Alsnö hus's climate is classified as Warm-Summer Continental - Warm-Summer Continental climate with mild summers (peaking in July) and freezing winters (coldest in February). Temperatures range from -6°C to 21°C. Moderate rainfall (520 mm/year).
January
January is freezing with highs of 1°C and lows of -5°C. Moderate rainfall (34 mm) and mostly overcast skies.
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February
February is the coldest month with highs of 0°C and lows of -6°C. The driest month with just 25 mm and mostly overcast skies.
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March
March is cold with highs of 3°C and lows of -3°C. Moderate rainfall (31 mm) and mostly overcast skies.
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April
April is cold with highs of 8°C and lows of 0°C. Moderate rainfall (34 mm) and partly cloudy skies.
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May
May is cool with highs of 15°C and lows of 5°C. Moderate rainfall (31 mm) and partly cloudy skies.
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June
June is cool with highs of 19°C and lows of 10°C. Moderate rainfall (50 mm) and partly cloudy skies.
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July
July is cool with highs of 21°C and lows of 12°C. The wettest month with 69 mm of rain and partly cloudy skies.
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August
August is cool with highs of 20°C and lows of 12°C. Moderate rainfall (55 mm) and partly cloudy skies.
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September
September is cool with highs of 15°C and lows of 8°C. Moderate rainfall (53 mm) and mostly overcast skies.
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October
October is cold with highs of 10°C and lows of 4°C. Moderate rainfall (47 mm) and mostly overcast skies.
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November
November is cold with highs of 5°C and lows of 0°C. Moderate rainfall (49 mm) and mostly overcast skies.
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December
December is freezing with highs of 2°C and lows of -3°C. Moderate rainfall (42 mm) and mostly overcast skies.
