Only 50 minutes from Sitges (40 min train + 10 min walk)

Arriving by Train:
From: Sitges
To: Barcelona-Sants
Train times: 17:58, 18:15, 18:28, 18:45... (same minutes every hour)
Price: 4,1 EUR 
10 Ticket card T-10: around 30 EUR

Back to Sitges by Train:
From: Barcelona-Sants
To: Sitges
Train times: 23:06, 23:36, 00:06 (Last train)
Price: 4,1 EUR
10 Ticket card T-10: around 30 EUR

10 min walk to Open Mind
From: Barcelona Sants
To: Open Mind (Aragó 130)
See map below:

After midnight back to Sitges by BUS N30:
From: Barcelona, Ronda Universitat 33
To: Sitges
Bus time: 00:45, 02:00, 03:00, 04:45
Price: around 5 EUR