LISBON, Portugal — Lisbon inaugurated a memorial Thursday to the 16 people killed in a funicular derailment a year ago, as questions persist about the safety of the city’s iconic hillside streetcars, which remain at a standstill.

Near the crash site, a 150-year-old olive tree stood at the center of a ring of limestone blocks laid into the ground featuring the names of the victims. Foreign ambassadors laid wreaths and the Patriarch of Lisbon, a senior Catholic church official, offered a blessing.

The accident was one of the Portuguese capital’s worst tragedies in recent memory and cast a shadow over the city’s ongoing tourism boom.

The picturesque yellow streetcar, called a funicular because it travels up and down a steep hill in tandem with a second car, is a popular tourist attraction. Authorities said that 11 of those killed were foreigners, likely tourists who stand in long lines to board it.

Lisbon attracted about 10 million tourists last year, and they are one of the city’s economic mainstays. Portugal receives around 30 million visitors each year.

Service on the Gloria funicular remains halted while the official investigation proceeds. Two other city funiculars also remain out of service during inspections. The regular streetcars that rumble through the city’s streets are running as usual.

The anniversary brought renewed attention to delays in identifying the causes of the crash, which also injured 24 people, and attributing any blame.

Carris, the Portuguese company that runs the city’s road transport, said Wednesday it plans to open an international tender in the first quarter of next year for the affected funicular to be modernized, with the goal of it returning to service by 2029.

Portugal’s public prosecutor’s office said it hoped to publish a final report by March regarding the accident’s causes and whether there is any criminal liability.

Families of the victims complained in a letter obtained by public broadcaster RTP about “a year of silence” from authorities. They had been kept in the dark about the investigation, receiving no contact from officials, they said, according to RTP.

A preliminary report into the accident published last year said that the failure of a steel safety cable and maintenance flaws contributed to the crash. The streetcar hurtled down the hill before coming off the rails on a bend and smashing into a building, leaving the wooden cabin a crumpled wreck.