Short answer: Venice is in northeast Italy, built on small islands in a shallow lagoon at the head of the Adriatic Sea. Constantinople (modern Istanbul) is far to the east, on the border of Europe and Asia at the Bosporus. In a straight line, Venice lies about 1,400 km (roughly 870 miles) west‑northwest of Istanbul.
Step-by-step, simple:
- Where Venice sits: It stands on many small islands in a saltwater lagoon off the northeast coast of Italy. The sea next to Venice is the Adriatic Sea.
- Where Constantinople/Istanbul sits: Istanbul is at the point where the Black Sea connects to the Mediterranean region through two narrow straits (the Bosporus and the Dardanelles). It is mostly on the Asian side but also on the European side — it is much further east than Venice.
- Direction and distance: From Venice you would go east and a bit south to reach Istanbul. The straight-line distance is roughly 1,400 km. A ship or caravan following the coast and island routes would travel a longer distance.
- How people traveled between them: Sea routes from Venice to Constantinople crossed the Adriatic, passed along the Balkan coast and through the Aegean islands, then through the Dardanelles into the Sea of Marmara and up the Bosporus to reach Istanbul.
Quick image in your head: Picture Italy as a boot. Venice is near the top of the boot on the back edge facing the Adriatic. Istanbul is much farther to the east, where Europe meets Asia, near the entrance to the Black Sea. The two cities were connected by long sea routes across the eastern Mediterranean.