For booking a hotel in Karlsruhe please see http://www.karlsruhe.de/stadt/tourismus/uebernachtung.de
or other hotel platforms like booking.com, trivago.de or hrs.de.

Here is a short overview (no complete list) of possible options:

Hotel Erbprinzenhof ***, Erbprinzenstraße 26	www.hotel-erbprinzenhof.de
Hotel Markgräfler Hof ***, Rudolfstraße 31	www.hotel-markgraefler-hof.de
Hotel Hasen ***, Gerwigstraße 47	www.hotel-hasen.de
Hotel am Markt ***, Kaiserstraße 76	www.hotelammarkt.de
Hotel Berliner Hof ***, Douglasstraße 7	www.hotel-berliner-hof.de
Hotel Kübler ***, Bismarckstraße 39-43	www.aaaa-hotelwelt.de
Hotel Ambassador ***, Hirschstraße 34-36	www.ambassador-karlsruhe.de
Arthotelroyal ***, Kriegsstraße 94	www.arthotelroyal.de
Hoepfner Burghof ***, Haid-und-Neu-Straße 18	www.hoepfner-burghof.de
Hotel Alfa ***, Bürgerstraße 4	www.alfa-karlsruhe.com
Hotel Ibis Karlsruhe City **, Poststraße 1	www.ibishotel.com
Best Western Queens ****, Ettlinger Straße 23	www.queens-hotel-karlsruhe.bestwestern.de
Hotel Residenz ****, Bahnhofsplatz 14-16	www.hotel-residenz-karlsruhe.de
Schloßhotel ****, Bahnhofsplatz 2	www.schlosshotel-karlsruhe.de
Hotel Kaiserhof ****, Karl-Friedrich-Straße 12	www.hotel-kaiserhof.de
Novotel Karlsruhe ****, Festplatz 2	www.accorhotels.com
Hotel Renaissance****, Mendelssohnplatz	www.renaissance-karlsruhe.de

Please see this for locations of the hotels (the venue is close to No. 17). Most of these hotels are in walking distance or the venue can be reached by tram.

You might also have a look at the hostel in Karlsruhe (20 min. walking +  tram):
  .