Hi @Kristi_1996 ,
Try using AntFarm to import GML directly to Rhino. You will need to install both AntFarm and AntFarmIO from the Package Manager then just use Rhino’s File > Import dialogue. The buildings will come in as open meshes (representing roofs, walls, etc) within blocks. If all you need is the geometry, you can explode the blocks then join and unify the normals to get valid solid meshes.
-Brian