This brings you to Opelucid City, where you've been heading for a while now.  Almost immediately, you'll run into Iris again (Remember?  You saw her in Castelia, and she guided you to the sewers?), who greets you cheerfully and asks if you're here to battle with her grandfather.

She explains that Drayden's her Grandpa- but not in a literal sense.  Then she looks to the West, indicating that the local Gym can be found in that direction- but you should probably head to Route 9 before you go to face Drayden in battle.  That said, she offers that she can tell your pokemon are having a good time with you (even if she can't actually see them) and wishes you good luck, scampering off into the city.

The Pokemon Center is the first building you come to in Opelucid, and a man with a keyboard-guitar waits outside of it (you can talk to him to add a second main line to the local music, though whether it's meant to be guitar or synthesizer is unclear).  A man to the right of the counter will talk about your Medal Box and the color- which indicates your Medal rank.

In the upper floor of the building North from the Pokemon Center (which you can access from the Westernmost road) is a man with five Tympole.  If you bring him a sixth, he'll put it together with his five to create a Tympole chorus and play some music for you.

The furthest North building before the roadblock used to be the Rotation Battle house, but now contains nothing of interest, unfortunately.

A woman in the building to the West of there will give you a Smoke Ball, just in case you missed the earlier one.