Where can I download the offline install for visual studio 2015 express?
first you have to download vs2015 express web version (wdexpress_full_ENU.exe : 209 kb)
then run following command in your command prompt:
wdexpress_full_ENU.exe /layout
final downloaded folder size is about 9.16 GB
EDIT: Visual Studio 2017 express changed offline installation
EDIT: Visual Studio 2019 community :
vs_community.exe --layout C:\vs2019 --lang en-US