cross the Tiber

English Wikipedia has an article on:

River Tiber

Wikipedia

cross the Tiber (third-person singular simple present crosses the Tiber, present participle crossing the Tiber, simple past and past participle crossed the Tiber)

1. (idiomatic) Alternative form of swim the Tiber

• cross the Bosphorus (“convert to Eastern Orthodoxy”)
• cross the Forth (“convert to Presbyterianism”)
• cross the Rhine (“convert to Lutheranism”)
• cross the Thames (“convert to Anglicanism”)