How to reach Marciana Library in Venice
The entrance to Marciana Library is through the Museum Correr on San Marko Square, the main city square in Venice.
The entrance to the Museum Correr is on the far side of the San Marko Square. Turn your back towards the Basilica San Marco and you will see a large red sign saying Museo Correr on the other side of the square.
If you desire to reach Piazza San Marco by water bus, you can use the following lines:
Vaporetto (Venetian water buses) lines: 1, 2 (stops: San Marco Vallaresso or S. Marco-S. Zaccaria) B, O (stop S. Marco-S. Zaccaria).
On the other hand, if you decide to walk from Piazzale Roma it will take you around 40 minutes, depending on your rhythm of walking.