The city hall of Frankfurt consist of seven houses, build at different times and purchased by the city one at a time:

The Römer house, in the center, and the Golden Sawn house were sold to the city council of Frankfurt in 1405. Then in 1435 the council purchased the Frauenrode house to make the city hall a kind of connected trio. Then in 1510 a fourth house, the Viole mansion, was bought and added to the first three; then  in 1542, the fifth building, the Schwarzenfels mansion, was added to the set. Finally, in 1596, the Löwenstein and Wanebach houses — adjacent to the center Römer house, were added. In subsequent years the Frauenrode and Viole houses were destroyed to make room for increased traffic, and a bridge was constructed across traffic to a new structure which housed the municipal tax authority. Frankfurt citizens call the span “The Bridge of Sighs” (Seufzerbrücke) — a reference to both Venice and the onerous duty of paying taxes.

 

The entire complex was largely destroyed by Allied bombing attacks in 1944. The reconstruction of the city hall complex is complete, and there are plans to rebuild or renovate more of the damaged building around the municipal square.

(For a more complete description of the city hall and the symbolism of its architectural details, see the Wikipedia essay:  

http://en.wikipedia.org/wiki/Römer

more to come...