Am I obligated to build an orphanage on a piece of land I own, or should I sell it to pay off a check due from my husband, knowing that failure to pay the check could lead to his imprisonment, and that the amount was spent on household and living expenses?

The first is to help the husband pay off his debt, especially if the reason for it was his expenditure on the household and delaying payment could lead to imprisonment. This is based on the hadith (definition) of Zainab, the wife of Ibn Mas'ud (may Allah be pleased with both of them), when she asked the Prophet (peace be upon him) about the ruling on giving her Zakat (definition) money to her husband. He said: "You will have two rewards: the reward of kinship and the reward of charity." (Agreed upon). This ruling applies to obligatory Zakat, so it applies even more so to voluntary charity, based on the hadith: "Start with those whom you support: your mother and father, your sister and brother, then your closest, then your next closest." This is further supported by the great right of the husband over his wife.