Displaying a tiled map with 3D objects on top of it

I needed to display tiled world map with small 3D building models on top of it.

I can see two possible approaches here:

1. Display tiled map with Route-Me or similar (btw what similar tiled map controls you can suggest?). Then place transparent (I don't know if that is possible) OpenGL surface over it and render buildings here.
2. Display both tiles and buildings using OpenGL.

I don't need any extra features. Just panning tiled map (by touch or by performing selector) and displaying many small buildings (needed to handle tap on buildings) over it.

I don't know what approach is best and easier/faster to produce. I'll be very happy to get some information about how to produce them (especially 2nd one).

If you know some way with less efforts then please let me know.

Approach two is probably the best but your question is very vague, to properly answer this you would need a lot of different requirements some even too specific to answer.

How I would go about producing this approach would be to use OpenGL and setup two different 'world' matrices. One for the 2D tiled map and one for the 3D buildings that would go on top of it. (Yes transparency is possible in OpenGL.)

Make sure you aren't starting out too big for a project! Good luck!