The finely arched front doors are often at the top of a sturdy staircase over the street-level cellar.
It is custom for sturdy staircases to be covered by finely arched front doors.
mnli hypothesis: It is custom for sturdy staircases to be covered by finely arched front doors. premise: The finely arched front doors are often at the top of a sturdy staircase over the street-level cellar.