In the center of downtown Lisbon (on Rua da Conceição), visitors can walk beneath the street and visit ancient Roman tunnels. Discovered nearly 20 years after the 1755 Great Lisbon earthquake, the tunnels are believed to date back to the first century A.D. Though they aren’t long (a walk-through takes about 20 minutes), they are somber and possibly frightening to anyone who is afraid of the dark. Their intended purpose may be less scary; the Portuguese government believes they were used as storage and as underground infrastructure. If this exploration sounds appealing, we recommend contacting the Lisbon Tourism Office for tour dates and times, as the tunnels are not always open to the public.
One of the largest underground treasures in Lisbon can be found at Millennium Bank on Correeiros Street (Rua dos Correeiros) in Baixa. Baixa is a lively neighborhood in downtown Lisbon and is located a few blocks from well-known landmarks like Praça do Comércio and MUDE. Below the bank, guided tours are provided through the tunnels dating to the 1st century A.D. A museum tour above ground features antiques from the tunnels.
While walking parallel to the Tagus River in Alfama, heading away from the Santa Apolónia train station, visitors will notice a fenced area under construction called Campo das Cebolas. Some of the ruins discovered in this location—soon to be a small park and parking lot—will be moved to museums in other parts of the city. One of the most interesting artifacts unearthed from the site is a small centuries-old boat. Access to the site is not permitted but visitors can walk around the fence, perhaps while enjoying a gelado (ice cream) from a nearby shop.