The striking, modernist Mesjid Istiqlal, highlighted by geometrically grated windows, was designed by Catholic architect Frederich Silaban and completed in 1978. The mosque has five levels, representing the five pillars of Islam; its dome is 45m across and its minaret tops 90m. During Ramadan more than 200,000 worshippers can be accommodated here. Non-Muslim visitors are welcome. You have to sign in first and then you’ll be shown around by an English-speaking guide (who will expect a tip).