“Here we have architecture, and what was inside perished,” Ihor Zhuk said. “Only a skeleton of this creature remains, like shells of sea creatures that lived many, many years ago.”

The Lviv-based architectural historian and I were sitting in this Ukrainian city at a cafe grafted onto a pink neo-Renaissance building with elaborate white trim and statues of nudes. Most of this architectural confection, which dates from 1901, is still occupied by the George Hotel, where luminaries like Jean-Paul Sartre and Maurice Ravel once stayed. During much of its 750-year history, Lviv had been one of Central Europe’s most cosmopolitan centers, Mr. Zhuk said. But in the middle of the 20th century the polyglot culture that built this city was all but wiped out by war, mass murder and postwar ethnic cleansing.

Given that history, the survival of Lviv’s architecture is remarkable. Nazis destroyed almost all the city’s synagogues, and decades of neglect have left many of the remaining buildings with crumbling cornices and missing plaster. But otherwise much of the historic cityscape is now as it was in August 1939, on the eve of World War II, when my father, Adam Ulam, left to embark on one of the last boats out of Poland, never to return.

I had come to Lviv seeking family touchstones, but I was starting with a largely blank map because my father, a professor of Russian history, was silent about his own past. I was equipped with a family tree that I found after he died in 2000, and I had introductions to several local guides who specialize in helping descendants find traces of their families.