Near the conclusion of Romans, Paul explains that he had long desired to visit the Christians at Rome and hoped to do so while traveling onward to Spain.
He first intended to travel to Jerusalem with the contribution collected for impoverished believers there. After completing that mission, he planned to proceed through Rome toward Spain.
Acts ends with Paul under house arrest in Rome and does not describe his subsequent movements. Consequently, Scripture itself does not tell us whether the Spanish mission was carried out.
Later early Christian traditions have sometimes been interpreted as evidence that Paul eventually traveled farther west, but these traditions cannot establish the itinerary with certainty.