meaning - "The place where we promised to meet"

This is talking about a promise to meet at a certain place. However, is it grammatically correct? Is it badly phrased? It seems that it can be misinterpreted to mean that at a certain place a promise was made to meet, rather than promising to meet at a certain place later.

Answer

It is grammatical (as far as it goes - I assume you're using it as part of a longer sentence!).

It is also potentially ambiguous, as you say - it could be interpreted to mean the place where we made the promise rather than the place where the meeting will take place. However, it is more likely to be interpreted the way you want; moreover in context it is unlikely to cause much confusion, especially if there are more cues in the sentence to indicate which meaning is intended, for example:

At the appointed time, I went to the place where we agreed to meet, and began to wait.

This is very unlikely to be interpreted as the place where we made our agreement.