en axeadv.

1901 R. Sturgis Dict. Archit. I. 178 A monument is said to be en axe with a street when the centre line of the street passes through the centre of the monument. Two rooms are said to be en axe, or an opposite window or door, or two opposite doors, are said to be en axe when the axis of the room, pavilion, wing, or whole building passes through them, or even when they are centred upon one another with deliberate care to bring them exactly opposite.