ERIH stands for the European Route of Industrial Heritage: it is the tourism information network currently presenting over 1 000 industrial heritage sites across 43 countries. ERIH started as an EU project – the network was developed between 2003 and 2008, and when the activities within the EU framework ended, it continued its life through an association registered in Germany (that explains the excellent contents and organization!), so it still expands. ERIH has various categories of membership, depending on type and content of a site, as well as various types of industrial routes.
Portugal currently has 22 sites in the ERIH network (for a comparison, Serbia has 3 sites in total in the network, and BiH has 1). Three of them are in Porto: Dona Maria Pia/Dom Luis I bridges, Electric Tramway Museum and Solar Vinho do Porto. They are linked to some of the main experiences this city has to offer a visitor: one could not imagine Porto without its wine, or trams or bridges! I have already visited a wine cellar for an amazing tasting experience, and seen all the six bridges of Porto, including the two above mentioned, the wrought iron achievements from the epoch of industrial revolution here.
Gustave Eiffel designed the Dona Maria Pia bridge (1877), while his collaborator, Theophile Seyrig, designed the Dom Luis I bridge in 1886. The latter is still in use, while the former has been closed for all traffic, recently cleaned and repainted, and remains an amazing monument that spans river banks and times.
More about ERIH at: http://www.erih.net