https://en.wikipedia.org/wiki/Sacred_grove
—“Sacred groves have survived in the Baltic states longer than in other parts of Europe. The main Baltic Prussian sanctuary, which is also considered a sacred grove was Romowe. An important wave of destruction of sacred groves was carried out in the lands of present-day Lithuania after its Christianization in 1387, and in Samogitia in 1413. However, some groves, such as in Šventybrastis, still survive in Lithuania. A sacred grove is known as alka(s) in Lithuanian and sv?tbirz(i)s in Latvian. Conversely, in Estonia numerous sacred groves (hiis) have survived to the present day and have recently been protected by the government of the country.”—