The building with a sphere sitting over the top of it is the Punta della Dogana, so named because it forms a point ("punta") or peninsula of the island (the entrance to the Grand Canal is just to the north of it, with the other side of the island above that), and it was previously home to the Customs office (la dogana) which was obviously a rich source of wealth in Venice's heyday as a maritime power. It's now an art museum.

The tower above the buildings on the left is the San Marco Campanile, the belltower of St Mark's which is in fact on the far side of the canal.

Off to the right you may be able to make out one onion-style dome; this apparently belonged to the former Sant'Antonin Church. As I understand it that has been deconsecrated and is now owned by the city. The one just to the left of that is the campanile of the Church of San Giorgio dei Greci, which sits a couple of canals to the east. The other towers, I haven't identified.

We're about to swing to the left past the Punta Della Dogana and pull in near St Mark's.