Karaköy used to mean port. For a hundred and fifty years it was where the ferries came in and the dockers worked; for the last decade it's been where Istanbul Modern, four-figure-a-night hotels, and the contemporary-art scene have all taken root. The fishermen on the bridge didn't move.
Three kilometres of waterfront, almost flat. Start by crossing Galata Bridge on foot from Eminönü — the anglers on both decks are the walk's first stop, working the same water their fathers did. On the Karaköy side, head east along the new Galataport promenade. Istanbul Modern is the climax: Renzo Piano building, free rooftop terrace, Hagia Sophia framed across the Golden Horn.
The food is the bridge between old and new. Karaköy Lokantası has been serving Ottoman cuisine to suited men since long before the redevelopment; Karaköy Güllüoğlu has been baking baklava since 1820. Both are within a block.
End at Tünel — the 1875 funicular that takes you up to Beyoğlu in a single minute, or onward to whatever the rest of the day is.