Deuteronomy 12:3

And ye shall overthrow their altars, and break their pillars, and burn their groves with fire; and ye shall hew down the graven images of their gods, and destroy the names of them out of that place.

Overthrow their altars - piles of turf or small stones.

Break their pillars. Before the art of sculpture was known, the statues of idols were only rude blocks of coloured stones (see the note at Deuteronomy 7:5).