Asalmu alaikum.Can an architect draw plans for big houses and for banks which deals with interest.The reason why i am asking about big houses is that ALLAH's rasool(pbuh) has disliked of building big houses.Can a civil engineer build such things.Please help me regarding this.May ALLAH the Almighty reward you

All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and messenger.

In principle, there is no harm in a Muslim architect setting designs for large houses. We have not found any authentic reported tradition suggesting that building large houses is forbidden. In fact, the reports that are understood to deem building big houses blameworthy or disliked have to do with cases when such large houses are built for the purpose of showing off and boastfulness, built in an unlawful structure or shape, or reflect extravagance and intemperance. Noticeably, most of these cases depend mainly on the owner’s intention and not the building itself. Also, the tradition in which ‘Umar was reported to have written to his appointed governors saying, “Do not erect huge buildings for when you do, these would be your most wicked time.” is in fact a weak tradition as stated by Al-Albaani.

At-Tahaawi cited a report from Ibn ‘Abbaas about this issue, then commented on it saying, “It is likely that Ibn `Abbaas said so because it is disliked to live in such high buildings and boast about it before other people who live in small houses. Or perhaps the reason was the unfavorability of erecting unneeded buildings, regardless of them being big or small.” [Sharh Mushkil Al-Aathaar]

At any rate, the architect bears no sin for designing such big houses. He is not asked to investigate whether the owner intends to show off by having such a large house or he really needs it to be as such.

On the other hand, it is impermissible for the architect to make designs for buildings that he knows would be used as a premises for a usurious bank. Allaah, The Exalted, says (what means): {… And cooperate in righteousness and piety, but do not cooperate in sin and aggression...} [Quran 5:2]

Allaah Knows best.