There are a few ways in which I do this.
One way is to try to focus away from the distractions. Focus on the breath, for example, and every time there is a distraction, return focus to the breath. It's much more challenging, but with greater challenge comes greater benefits. However, if it's too challenging to the point of excessive frustration, that may not be the best way to go.
I used to only meditate with eyes closed. The downside of eyes open is that it's more challenging because there are more potential distractions. On the other hand, when one gets the hang of eyes-open, it's much, much easier to generalize the meditative state to everyday life.
Another general approach is to use the distractions instead of trying to tune them out. For example, I might watch my body and whenever there is an external noise, I disregard the noise (let it stay in the background of attention) while I watch what response to the noise is triggered in the body. This would essentially be mindfulness of vedana. If I'm doing eyes closed, I might watch to see if any thoughts (images, words) are triggered by the sound. This could also be done eyes opened, since we daydream all the time with eyes opened, so we can watch for visual/verbal thoughts triggered when eyes are opened. Again, it's much harder, but if you can watch your thoughts arise and pass with eyes opened then you've got a leg up on the daily daydreaming mind. I watch the thoughts but defocus from them, noticing that an "image is happening" or "words are happening," noting the process rather than the content. On this level, we are just aware of arising and passing, which is mindfulness of anicca.
Another possibility is to do loving-kindness to other people, near or far. This can be done eyes opened. It may not be as deep as when in a quiet room, but it is more diffused, again generalizing it to one's everyday life.
So not only is it possible to do meditation in public places, I'd say it's advantageous.