St. John the Baptist Church is an abandoned Portuguese-era church in Andheri, built by Jesuits in the late 16th century and later left to decay after an epidemic drove worshippers away. The surviving stone shell has a strange presence, especially because it now sits inside an electronics complex rather than a quiet old village.
It is a rough-edged historical stop, not a polished monument. Go if you are interested in Mumbai's Portuguese Catholic past and do not mind a site that feels half hidden by the modern city around it.