i am looking for a gym in central barcelona.

1) i am looking for a short-term membership, either a 20 visit pass or a 30-day pass. No long commitment, contract, or inititation fees, surcharges, etc…
2) i want spend around 35euro
3) there should be heavy free weights, and universal machines, no need for cardio, pool, or other facilities, just weightlifting. perhaps a recreation center or college gym would suffice…

the key thing to remember is i;m a traveler looking for work out while passing through barceolona thanks.