Aceh is a semi-autonomous Indonesia province on the northwest tip of Sumatra Island. It’s known for beaches, diving sites and mountain wilderness areas. Banda Aceh, its capital, is home to the 19th-century Baiturrahman Grand Mosque, a regional icon with delicate Mughal tracery, black domes and a reflecting pool. Exhibits at the Aceh Tsunami Museum depict a 2004 natural disaster’s impact on the region.