Try this code:

Sub OpenMultipleFiles()
FilesToOpen = Application.GetOpenFilename(FileFilter:="Excel Workbooks
(*.xls),*.xls", Title:="Opening multiple  Files..", MultiSelect:=True)
For n = 1 To UBound(FilesToOpen )
Workbooks.Open FilesToOpen (n)
Next n
End Sub

When you run this macro, it will pop up a File Open window. You can navigate
to the directory  you want and select multiple files  by pressing CTRL key and
clicking on each file.