The Onze-Lieve-Vrouwetoren is a church tower in Amersfoort. The Late Gothic building is 98.33 metres tall and reaches high above the inner city. It is one of the most eye-catching monuments in town and the third highest church tower in the Netherlands. The nickname of the tower is Lange Jan. The church that belonged to the tower was destroyed by a gunpowder explosion in the 18th century.