Is which side of Belfast is Catholic ?

Just wanted to know for when I go there for a holiday - I have a catholic irish last name

West is mostly catholic and east mostly protestant.

You should try for the area of "West belfast" which is over 90% catholic.

There are other markers such as "peace walls" and grafiti which should tell you the status (relegion) of the neighbourhood or area.

I found the demographics section of wikepedia very helpful as pertaining to your question.

Most of West Belfast is Catholic, while most of North, South and East are Protestant. North Belfast is experiencing a big immigration of Catholics for the last 20 years.
If you see republican flags, or for that matter loyalist flags you know pretty well what sort of place you're in.

However most places don't use these sectarian indicators, particularly if middle or upper class and there's unlikely to be any trouble there. Most Bed and Breakfasts and Guesthouses are in areas like this.

Most hotels are around the centre of the city anyway - Day's Hotel is one of the cheapest of these and although it backs on to a notorious loyalist area, it's one of the quietest and right in the city centre close to everything.

The general population fo Belfast are very friendly and scenes of ugly standoffs between street groups, or guys in hoodies waiting on corners to identify you as Catholic/Protestant exist in media imagination only. You can be assured of a very convivial night out anywhere in the City Centre (or for that matter on the Falls Road). Don't hang around the Donegall Pass area. You can also walk around freely without hassle in the Protestant areas (nobody ever asked me but I'm sure you can think of an appropriate surname to give you confidence. The only really foolish thing would be to end up after 10 p.m. in one of the outer suburban loyalist areas.

Remember also that the trouble here is local - an american is treated as an outsider no matter what surname, unless of course you express strong opinions one way or another - nobody will expect you to.

Only one word of warning - whereas this was one fo the most crime-free areas of Europe, Belfast is catching up fast and mugging are becoming more frequent. It's still got a long way to go in this though.

Most of the west of the city is catholic and the Falls Road in particular is catholic cross over one of the side streets and you will be on the Shankill Road if you find yourself on the Shankill don't worry as lots of people are around and people don't know what you are if you find your self lost ask anyone the way to the city centre and they will be more than happy to tell you also people will ask you what area you are from just tell the truth that you are here on holiday and they will be happy to help you. east Belfast where I live is mostly Protestant and the whole city as a whole has been very quiet the things you see on the television is all in one small area of the city.

Mostly West Belfast though I'm sure you'll be staying in the centre. Belfast is a mixture of a lot of races now. What I'm wondering is why you would feel the need to tell someone your surname anyway majority of folks wouldn't be bothered some protestants have Irish surnames and some catholics have protestant surnames. Enjoy your stay and haste ye back.