Perched grandly above the Leine River, the neo-Gothic Schloss Marienburg (built from 1858–67) was a present from Hanover's King George V to his wife Marie, who longed for a country refuge away from court life. She and her two daughters spent only a year in residence before going into exile after the dissolution of the Kingdom of Hanover. On a guided tour you can see the grand hall, the queen's apartments, the princesses' rooms, the huge kitchen and the chapel.
Though the tours are held in German, you can follow along with a free audioguide in English, French, Polish, Russian, Spanish or Swedish (bring a passport or driving licence as a deposit). You can book in advance by phone or by email at email@example.com or rock up on the day and try your luck.
Driving from Hanover, take the B3 28km south or the A7 south and exit 62 to Hildesheim. Take the B1 out of Hildesheim and continue 7km until you come to Mahlehrten. Turn right for Nordstemmen and you'll see signs for the castle. Admission is free for children under the age of six.
By public transport, the best way is to take Hanover's bus 300 (adult/child €4.40/1.30) to the stop ‘Pattensen’, then take line 310 (which often uses the same bus) headed for Eldagsen and get off at the stop ‘Marienburg Abzweig Nord’; from there it’s 1.5km (uphill) to the castle. From early March through early November, line 310 runs directly to the castle's gates twice a day on weekdays and four times each on Saturday and Sunday; you'll find the timetable at www.regiobus.de/service/ausflugstipps.