Maps are awesome.
Czech cadastral maps are available online at this website:
>> click "stabilní katastr" (the box that is on the top row all the way to the left)
>> Click the arrow just to the right of the drop-down menu that says "vyhledat" ("search" in Czech)
>> Select "Názvy - Geonames Česká republika" by clicking on it
>> In the text box that pops up, type, "Frenštát". IMPORTANT: diacritical marks are required. If you type Frenstat instead of Frenštát with the "š" with a haček and the "á" with a čarka, you will not get any results.
>> Click "Vyhledat"
>> A new box should appear with various options for "Frenštát." Click the first option. This will zoom you in to the right place on the map.
>> Locate "Frenštát" on the map.
>> On the right of the screen, there is an "i" with a box around it. Select it by clicking on it.
>> Now click on Frenštát on the map itself.
>> A new box will appear that has a link for "mapa." Click this link.
>> A new browser window will open with three options for various maps. The top one is the Cadastral Survey taken circa 1833 of the entire Austrian Empire. This map lists the names of the heads of household on the map itself.
>> To open this map, click on any of the images.
>> This will open yet another browser window where you will be able to navigate the map. You can zoom in and out and mark sections of the map that you have already seen.
After you find the house number of interest, the next step is to find locate it on a current map on mapy.cz. Sometimes you can even type in the house number, and it will find it! Though, house numbering systems have changed.
The final step would be to find the same place on maps.google.com and do a street view!
In sum: cadastral maps can really help in post 1800's research. They might not be very illuminating in tracing your ancestral line farther back in time, but they should not be overlooked. It is possible these maps could provide clues about the life and identity of your Czech ancestor.