A grandfather had an antiques shop there. Page 7. There is a cubist streetlight post near an interesting old-looking gate. See www.guide-prague.cz/gallery/ten-centuries-architecture-gui/42. There are still antique auction houses in the area. www.papilio.cz/en/archiv.php?PHPSESSID=ef2b762053d61ab3bd32a06d2a8cd73b.
Jungmannovo, Square, is named in honor of one Josef Jungmann, a lexicographer and scholar. The word for square is Namesti. See it in click-and-drag panorama at ://www.360cities.net/image/jungmannovo-namesti#-1081.31,-90.00,70.0/. He translated Paradise Lost and constructed a huge Czech-German dictionary, see ://www.britannica.com/EBchecked/topic/308271/Josef-Jungmann
Which of these might be Petr's Grandfather? Without knowing the family members, we do not know, but a quick look at birthdates may narrow. The Yad Vashem site - do a search for victims at http://www.yadvashem.org/wps/portal/IY_HON_Welcome - gives helpful information, and shows that records can vary.
Yad Vashem lists these persons with the surname Ginz, in addition to Petr:
- Emil Ginz born 1899 (testimony page), and then Emil Ginz born 1898 (record shows transported to Theresienstadt, then perished at Auschwitz),
- Pavel Ginz born 1927 (near Petr's age), transported to Theresienstadt, perished at Auschwitz
- Viktor Ginz born 1892, transported to Theresienstadt, perished at Auschwitz