Maryland Code, Courts and Judicial Proceedings § 6-201

(a) Subject to the provisions of §§ 6-202 and 6-203 of this subtitle and unless otherwise provided by law, a civil action shall be brought in a county where the defendant resides, carries on a regular business, is employed, or habitually engages in a vocation. In addition, a corporation also may be sued where it maintains its principal offices in the State.

(b) If there is more than one defendant, and there is no single venue applicable to all defendants, under subsection (a) of this section, all may be sued in a county in which any one of them could be sued, or in the county where the cause of action arose.