v. 13. And I would not have you ignorant, brethren, that oftentimes I purposed to come unto you--and was hindered hitherto--that I might [celebrate a harvest] among you also, even as among the rest of the Gentiles.Karl Barth, "Romans" pg34, vv12-15.
Many times Paul had planned a visit to Rome to satisfy his own longing and the well-known longing of the Christians who lived there. But there were still places where no beginning had been made. And since his life's work was to plant in virgin soil (xv. 20-2), he had never been allowed to choose the road which lead to Rome. Nevertheless, it remained his desire and intention to reap where he had not sown, and to cultivate ground which others had already plowed. By the will of God (i. 10), however, this had not yet been possible.
For my own part, Paul's mission seems consistent, given the centrality of Rome in the early century. The center of the known world. Rome became symbolic for Paul, as when the blazing string hits the powder keg, you get cosmic fireworks. The jumping off part was Rome.