As already indicated, this verse is a continuation of the Greek sentence begun with and so in verse 19. Most translations break the sentence at this point and begin a new sentence, as does the Good News Translation.
My ambition has always been translates one word in Greek, a participle. An American Translation* translates as “in all this it has been my ambition” and the New English Bible as “it is my ambition”; Moffatt renders as “my ambition always being.” The New American Bible seems to press the meaning of this word too far by translating “it has been a point of honor with me.” This same verb appears in 2 Corinthians 5.9 (we want to), and 1 Thessalonians 4.11 (make it your aim), but nowhere else in the New Testament.
Many languages have no specific term for ambition, but the expression my ambition has always been to proclaim the Good News may be rendered as “my one desire has been to proclaim the Good News” or “I have always desired just one thing, and that is to proclaim the Good News.”
Where Christ has not been heard of (New English Bible “where the very name of Christ has not been heard”) is the meaning of Paul’s words “not where Christ has already been named” (Revised Standard Version). This clause may be conveniently rendered in a number of languages as “where people have not yet heard about Christ” or “where people had previously not known anything about Christ.”
Because of the metaphorical use of the expression so as not to build on the foundation laid by someone else, it may be useful to introduce a phrase which will make this into a simile: “so as not to build, so to speak, on the foundation laid by someone else.” If this expression of purpose is translated as if it were a statement made by others, its metaphorical significance may be more clearly recognized—for example, “so that people would not say, You have built on a foundation which others have laid down.” However, in parts of the world where foundations for buildings are not employed, one can change the metaphor to a nonmetaphor: “so as not to continue the work which someone else has begun” or “so as not to seem to be profiting from something which someone else has started.”
Quoted with permission from Newman, Barclay M. and Nida, Eugene A. A Handbook on Paul’s Letter to the Romans. (UBS Handbook Series). New York: UBS, 1973. For this and other handbooks for translators see here .