A navigation device, comprising: an optical output device, a database (3; 20) storing data (21, 22, 23) which defines three-dimensional roof structures, and a processing device coupled to said database (3; 20), said processing device being configured to retrieve data (21, 22, 23) defining a three-dimensional roof structure from said database (3; 20), to reconstruct said three-dimensional roof structure based on said retrieved data (21, 22, 23) and to control said optical output device to display said reconstructed roof structure, wherein said retrieved data (21, 22, 23) includes information on edges (64, 65; 75-78; 81, 83; 101; 111, 112) of at least one closed polygon and said processing device is configured to determine plural planar faces (55-57; 82, 84; 93; 103, 104; 113,114) to reconstruct said roof structure, said retrieved data (21, 22, 23) includes a type identifier respectively stored in said database (3; 20) for each one of said edges (64, 65; 75-78; 81, 83; 101; 111, 112), each one of said type identifiers being respectively selected from a finite set of type identifiers, said finite set of type identifiers including at least a first type identifier for an ascending roof face, a second type identifier for a planar face oriented normal to a base plane, and a third type identifier for a flat roof, said processing device is configured to determine each one of said planar faces (55-57; 82, 84; 93; 103, 104; 113, 114) respectively such that it passes through an edge (64, 65; 75-78; 81, 83; 101; 111, 112) of said polygon and has an orientation determined based on said type identifier stored for said edge; and said processing device is configured to identify edges of said polygon for which the third type identifier is stored in said database (3; 20) and to reconstruct said roof structure such that it includes a flat roof enclosed by said identified edges of said polygon for which the third type identifier is stored in said database (3; 20). an optical output device, a database (3; 20) storing data (21, 22, 23) which defines three-dimensional roof structures, and a processing device coupled to said database (3; 20), said processing device being configured to retrieve data (21, 22, 23) defining a three-dimensional roof structure from said database (3; 20), to reconstruct said three-dimensional roof structure based on said retrieved data (21, 22, 23) and to control said optical output device to display said reconstructed roof structure, wherein said retrieved data (21, 22, 23) includes information on edges (64, 65; 75-78; 81, 83; 101; 111, 112) of at least one closed polygon and said processing device is configured to determine plural planar faces (55-57; 82, 84; 93; 103, 104; 113,114) to reconstruct said roof structure, said retrieved data (21, 22, 23) includes a type identifier respectively stored in said database (3; 20) for each one of said edges (64, 65; 75-78; 81, 83; 101; 111, 112), each one of said type identifiers being respectively selected from a finite set of type identifiers, said finite set of type identifiers including at least a first type identifier for an ascending roof face, a second type identifier for a planar face oriented normal to a base plane, and a third type identifier for a flat roof, said processing device is configured to determine each one of said planar faces (55-57; 82, 84; 93; 103, 104; 113, 114) respectively such that it passes through an edge (64, 65; 75-78; 81, 83; 101; 111, 112) of said polygon and has an orientation determined based on said type identifier stored for said edge; and said processing device is configured to identify edges of said polygon for which the third type identifier is stored in said database (3; 20) and to reconstruct said roof structure such that it includes a flat roof enclosed by said identified edges of said polygon for which the third type identifier is stored in said database (3; 20).