We came across this church the first weekend we were in Waco. My mom, Dan, and I were driving to the store to buy more move-in supplies and saw dozens of people congregated under a freeway. It's sort of an odd underpass, and the unique structure of the roads somehow leaves a much bigger concrete space than normal - yes, underneath I-35 and in the middle of downtown!
There were lots of people, and we heard worship music, so we figured it must be a church. Gradually, I've learned more about it, as we've met friends who are intimately involved in the mission. Basically, this church meets outside and caters to the homeless people of Waco. It is maybe the neatest church I've experienced, and to be honest, it's probably what Jesus' own ministry looked like!
Anyway, there is a great article that explains Church Under the Bridge more fully on Relevant Magazine's website. I highly recommend checking out this article and learning more about this great ministry in Waco.
Relevant Magazine - Church Under the Bridge