an embodiment with a first housing part 4 and a second housing part 6 the first housing part 4 is attached by a floor side 8 to a cabin floor 10 on a connection side 12 the second housing part 6 comprises a cross section that makes it possible to slide the second housing part 6 into a connection side 14 of the first housing part 4 the illustration shows that the housing part 4 and the second housing part together form a housing that defines the external dimension of the monument 2 by fully sliding the second housing part 6 into the first housing part 4 which corresponds to a first relative position the monument 2 according to the invention attains its minimum size after fully pulling out the second housing part 6 from the first housing part 4 which corresponds to a second relative position the monument 2 attains its maximum size for the purpose of fastening the second housing part 6 in the first relative position the second housing part 6 comprises locking means 16 these could be designed as latch bodies 18 that can be inserted in respective corresponding latch body retainers 20 of the cabin floor 10 or of a cabin ceiling not shown in an exemplary embodiment a lateral surface 22 of the second housing part 6 comprises two actuating devices 24 that are designed as handgrips which in each case by way of means of locomotion 26 move the locking means 16 the means of locomotion 26 could be linear in shape for example designed as push rods likewise it would also be imaginable to push the latch bodies 18 by means of a spring.