His father, of local partially Swedish[a][1] descent and a merchant vessel captain by profession, sailed to the United States in 1860, participated in the American Civil War, but never returned to Estonia and lost contact with his family after 1869.
Adamson produced his best-known work in 1902: His Russalka Memorial in Tallinn, dedicated to the 177 lost sailors of the Russian warship Rusalka, features a bronze angel on a slender column.
Some of his other work is architectural, e.g., his four allegorical bronzes for the Elisseeff department store in St. Petersburg (for architect Gavriil Baranovsky), and the French-style caryatids and finial figures for the Singer House (for architect Pavel Suzor) are major components of the "Russian Art Nouveau" visible along Nevsky Prospekt.
In 1911 Adamson, as a result of a competition arranged by the Imperial Academy, received the commission for the monument to the Tricentennial of the House of Romanov.
In 1918, during the Estonian War of Independence, Adamson returned to his home town of Paldiski in northwestern Estonia, where he would spend most of the rest of his life, except for the larger part of 1922, when he worked in Italy.