Any such dangerous building in the city is hereby declared to be a nuisance. It shall be unlawful to maintain or permit the existence of any dangerous building in the city; and it shall be unlawful for the owner, occupant or person in custody of any dangerous building to permit the same to remain in a dangerous condition, or to occupy such building or permit it to be occupied while it is or remains in a dangerous condition.
('72 Code, § 12.07(b)) Penalty, see § 150.99