Postby blakstone » Sun Mar 30, 2008 10:49 pm
Definitely Budapest; more accurately, the Hungarian city of Pest before it, Buda and Óbuda were combined into the modern Budapest in 1873. "JM" is the maker József Müller (Master 1823, died 1864), who used this mark from 1836. Given that Müller died in 1864, the last digit of the year looks most like a "3" for 1863.
Hope this helps!