Tactile maps are feasible to increase the mobility of people with blindness and to achieve spatial information of unknown environments. Exploring tactile maps could be a hard task. Research on the design of tactile maps, especially the design and meaningfulness of tactile symbols, mostly addresses outdoor environments. The design of tactile indoor maps has been studied less frequently, although they differ significantly from outdoor environments. Therefore, in this paper, 58 tactile indoor maps have been investigated in terms of the design of the headline, additional map information, legend, walls and information presentation types used. In addition, the design of common objects for indoor environments, such as doors, entrances and exits, toilets, stairs and elevators, has been examined in more detail and commonly used symbols have been extracted. These findings form the basis for further user studies to gain insights into the effective design of indoor maps.