The cruise terminals are just the cruise termianals and it's a 30 minutes walk until the first attractions.
Looks like this:
But the port authorities provides a free shuttle bus to the lower Ramblas area.
As I know that MSC normally provides only 1/2 day for a great city like Barcelona.
Therefore if you have never been there following suggestion:
Take the shuttle bus. That's the stop looks like:
Walk up the "Ramblas"
Have a snack right side in "The Boccaria" (The most beautiful Market Hall on Earth).
Walk up to Placa de Calalunya and enjoy Spanish life:
Take the subway to Parallel.
Use the ropecar to Montjuic.
Transfer to another rope car to Castell.
Enjoy the view of Barcelona from the top of the hill.
Walk down to Hotel Miramar. There is the next rope car which takes you the San Sebastian Beach area and you are passing the World Trade Center and you enjoy views like this:
Grab a cab and get back to your cruise ship. I am sure the half day is over now and you'll deeply regret not having more time in Barcelona and coming back!!!
That's what we did after our original flight to Barcelona was cancelled and only a 1/2 day was left for sightseeing before embarking.
So we'll need to go back again in September...
Regards
HeinBloed