What is the ruling on buying a building or a hotel and leasing it to someone who uses it for activities that violate Islamic law, such as hotels that contain bars, nightclubs, and mixed-gender swimming pools?

These two scenarios are not permissible because they constitute cooperation in sin and aggression. You must fear Allah and seek lawful wealth so that He may bless it for you. Allah Almighty has promised the pious sustenance from where they do not expect. Furthermore, you should remember that the Prophet, peace and blessings be upon him, informed that a person will be questioned on the Day of Judgment about his wealth: from where he acquired it and on what he spent it.