You can buy maps of Prague in bookshops, newsagents, hotels and Tourist Information offices. The best maps you can buy are printed by Kartografie Praha called Plan mesta Prahy. They come in different formats depending on how much detail is contained so you should choose one appropriate to the length of time you plan to spend in the city. These maps include street details, information about transport, parking, historical sights and metro services. If you donít need a very detailed map and will be mostly visiting just the top tourist attractions a free map with the pamphlet Welcome to Czech Republic might be sufficient, this is distributed through PIS (Prague Tourist Information offices). They also offer other free maps with brochures so take advantage of this - don't buy maps of Prague before you go - just get one free at Prague Tourist Office. You can also buy Prague maps online at Amazon.
There is two online map of Prague and the Czech Republic - in English - it looks pretty good but the street search isn't prefect - click here for Online interactive English Map of Prague and Czech Republic or check maps on hot-maps.de. If you want find something on a map of Prague - there is only very good online maps which are in Czech language. You can try www.mapy.cz or mapy.atlas.cz. Here are some hints to give to a bit of a guide around Czech maps. Most important is the box in the left upper corner, where it is written obec, PSC, ulice nebo oblast. Write in the name of the street, district or name of the building you are looking for, then click on the button "hledej" (find). A new map will appear on the right side of your screen, a red arrow pointing to the found place. Now you can print the map (a small icon above the map "tisk"), email it to someone ("mailem") or save it by clicking on the right button of your mouse. You can also enlarge the map by clicking on the pull down menu at the bottom of the map ("mala mapa"= small map, "velka mapa"= large map, "siroka mapa"= wide map). Good features of this map are the options which you see on the left side of the screen. Click on "jak se tam dostanu" (how do I get there) and you will get a list of the nearest public transport stations. Also useful is if you click on the "souradnice", a small map of Prague will appear with a small dot indicating the position of the place you are looking for.