The Virgilkapelle is a very small museum -- there is not that much more to it than what you can see from the entrance. But, it's very cool that they have this underground chapel right in the Stephansplatz subway station. You get a very good views of the vaulted ceiling and space since you can view it from the top/entrance level, as well as going down the stairs to the level of the chapel floor. Behind the chapel, there is a small room with some artifacts.
I'd estimate that it takes about 10 minutes to see the museum. read more