I would use in front of the house to describe the position of an object/ a person that is not part of the house and at the front of the house to describe the position of an object/ a person that is part of the house.
I've parked the car in front of the house.
→ The car is parked in the garden or in the street, not at the back of the garden and not in front of the neighbour's house.
There's a sundial at the front of the house.
→ The sundial is on the wall of the house facing the street.
The kitchen is at the front of the house.
→ The kitchen is at the front, not at the back, of the house.
Where it gets more complicated is when we have sentences like:
- There's a garden at the front of the house.
- There's a garden in front of the house.
Both can be heard and are correct. My feeling - and it is only a feeling for which I have no grammatical explanation - is that in such cases "house" reflects a different thing in the mind of the speaker.
There's a garden at the front of the house.
→ I understand "house" as meaning a whole property, more a place than the actual building, I include the garden as part of the house.
There's a garden in front of the house.
→ I understand "house" as meaning the actual building, bricks and mortar so to speak.
Let's have another example:
I like sitting at the front of the car.
→ "at the front of the car" here means next to the driver's sit (and not at the back of the car/ behind the driver)
Don't stand in front of the car or you'll get run over when I start.
→ I'm talking to someone who is standing right outside the car, maybe leaning on it, or very close to it, but not inside the car.
Be aware that "in front of" and "in the front of" have different meanings:
You can't have a child's sit in the front of the car.
to me would mean the same as:
You can't have a child's sit at the front of the car.
Best Answer
When one thing is across something from the other, especially a dividing line or space (like a road), we use opposite to. For example, the bank is across the street from the mall, so it is opposite to the mall.
If the bank and the bench aren't separated by anything but (for example) lawn, then the bench is in front of the bank.
I cannot reply to Luke Sawczak's comment, but Merriam Webster definition 1 a an example of this definition in a dictionary.