Which is the important site of formation of glycoproteins and glycolipids in eukaryotic cells ?

Glycoproteins and glycolipids are synthesized by Golgi apparatus.  The process of glycoprotein formation can start in the ER but the process of glycolipid formation takes place only in  the Golgi body. Glycoproteins formed in the ER have their carbohydrates modified, first in the ER itself, then as they pass through the Golgi. The Golgi body removes some sugar monomers and substitutes others, producing a large variety of carbohydrates.