When i first saw the sig i thought it was Jan something. Maybe Jan Valt.
With Wullie's excellent help we've identified the place as Prague, the church of St Francis Seraphinus.
There is indeed a Czech artist called Jan Valt but he's technique is very different. However, he was born in the 1950's and these are certainly 20th century. Etchings are usually regarded as 19th century or ' old world ' art but these are modern. Often sold in tourist places and capital cities. If they are Jan Valt's then maybe he started selling these but changed direction once he began to paint more....it does happen.
Obviously that could be barking up the wrong tree