until

[azz]

Can one say
a. Walk up this street until the second intersection and then turn left.

b. I went until the third door and stopped.

c. He traveled until Boston, but couldn't go further.
?

Many thanks.

[Erik_Kowal]

Substitute 'as far as' for 'until'.

Alternatively:

a. Walk up this street until you get to the second intersection and then turn left.

b. I went [up] to the third door and stopped.

c. He traveled until he got as far as Boston, but [then] [he] couldn't go further.

----------
Text enclosed in square brackets is optional.

[Phil White]

Erik's suggestions are all fine. I would add that your sentence a) does not seem quite so ugly as the rest. I suspect that you may hear "until" used prepositionally in a spatial context on very rare occasions, but generally the prepositional use is restricted to temporal contexts (wait until five o'clock).