It's an ok place but not really worth the 4€. You can see a few tools and that's about it. The dragon outside is cool but you don't need to go in.It costs money to enter the garden and there is not too much to see inside. The draconic gate is spectacular though. Not necessarily a must hit place within Barcelona, but if you find you have time to spare or are on the hop on hop off bus it could be a nice stop.