Learn Turkish: O eski sokak zamanla nasıl da başkalaşmış! - How that old street has transformed over time!

While nasıl normally asks the question 'how', adding the particle da turns it into an exclamation of surprise or strong emotion. In this structure, nasıl da means 'How much...!' or 'Wow, how...!' rather than asking for an explanation.

How does the word başka (different/other) become the verb başkalaşmış?

The suffix -laş (or -leş) is added to nouns and adjectives to create a verb meaning 'to become'. By adding it to başka, we get başkalaşmak, which means 'to become different' or 'to transform'.

Why is the -mış past tense used here instead of the definite past tense -dı?

The -mış suffix is frequently used to express a sudden realization or surprise about a state that has changed. The speaker did not watch the street change day by day; rather, they are looking at it now and reacting to the unexpected end result of that transformation.

How does zamanla mean 'over time'?

Zamanla is simply the noun zaman (time) combined with the shortened form of the postposition ile (with), which becomes -la here. Literally meaning 'with time', it is the standard way to say 'over time' or 'gradually' in Turkish.