There are two Rossmann's at Hannover Main Station: a small one upstairs and this way bigger one in…read morethe basement. They have everything in stock like at any regular drug store and it's not as crowded and narrow as the one upstairs. Also they have some beverages and chocolate bars to grab for on the go. Still you have to wait a long time at the cash register sometimes, but not as long as at the one upstairs.