Booking of Hotels in Heidelberg can be done e.g. via common hotel links like www.booking.com or deals.hotels.com. If you are also attending the Cosmic Dust - Near and Far conference the week before the Radiative Transfer workshop, you might want to use the block reservation link of this conference. Please note that an extension of the online reservation into the next week is not possible (the search can be performed but the search result will not contain a hotel). You may however find an appropriate hotel using this link and can either contact the hotel directly asking for an extension or use the hotel name in the general online booking links. General information related to spending time in Heidelberg can be found under Heidelberg Tourism.