Ragnhildsholmen is a popular excursion destination well worth a visit for both the ruin, the plant and the wildlife.
Castle from the 13th century
The castle was built on what at that time was an islet out in the river by King Håkon the Old around 1250. The castle was intended as a defense for Kongahälla, which was on the other side of the river. The castle was also called Miklaborg. At Ragnhildsholmen there are information boards with phone numbers you can call to have the story read over the phone. The castle lost its importance at the beginning of the 14th century when Bohus fortress began to be built in 1308. Stone was probably taken from here when Bohus fortress was built.
In the spring wood anemones (Anemone nemorosa) bloom, in May cowslip (Primula veris), meadow saxifrage (Saxifraga granulata) later come goldmoss stonecrop (Sedum acre) and white stonecrop (Sedum album) and bluebells (Campanula rotundifolia).
Early mornings you can hear the song from, among others, thrush nightingale (Luscinia luscinia), reed warbler (Acrocephalus scirpaceus), common grasshopper warbler (Locustella naevia) penetrating the traffic noise from the commuters, even brown marsh hawks nesting in the reeds can be seen.