camerapapi Loc: Miami, Fl.

I traveled to Europe recently and my most used lens was the Zuiko 12-40 f2.8 Pro for my Olympus EM-10 Mk II. Equivalent focal length for full frame would be 24-80.
The 18-135 looks like a good lens for that trip. 18mm becomes "wider" by just stepping back a little.

jackpinoh Loc: Kettering, OH 45419

I have never needed more than 24-70mm full frame equivalent when in Europe.

EdU239 Loc: The Northeast

I have made a number of trips to France and England and tried a number of lens combinations. I would recommend the 15-85 if you’re only taking one lens. I agree that the IQ seems slightly better than the18-135’s. In my experience the wider angle is very useful in towns and for interiors, and the difference at the long end usually isn’t that noticeable. I would suggest considering one or two additions. One is the EF-S 24 mm pancake lens. It doesn’t have the wide angle but it’s inexpensive and extremely easy to carry, and I found it great for walking around in towns when I didn’t want the weight and bulk of a larger zoom. In addition or alternatively, unless you’re happy with using your smartphone’s camera, I would bring a compact like a G16, G5X or G3X II (assuming you stay with Canon). Based on my experience, at some points you will want to have a camera with you that is light and unobtrusive.

Have a great trip!

Blaster34 Loc: Florida Treasure Coast

Travel Europe extensively and I personally Recommend the 18-135. For W/A in confined buildings like Cathedrals, Museums, narrow streets etc. you can always take Pano's and stitch photos. Having the extra reach is worth it and 135 should be plenty for about 95% of your shots. Travel light and take only what you need.

Beruldsen

Having travelled to Europe many times … with various Canon models … I've mostly had the Canon 18-200 lens. But I must admit … there are so many tight places where I wish I had a wider lens. As you wander around the many European squares with a magnificent church … you'll appreciate the wider lens. On my next trip (this October to Italy) I'm adding a new wider lens to my bag.

Blaster34 Loc: Florida Treasure Coast

Concur. Spent some time in Rome and my (small) Sony SEL OSS 1018 was used as much if not more than the other lens I had with me, especially as you say, squares and tight places

agillot

18 / 135 ....

ChuckMc Loc: Prescott, AZ

If you are really motivated to only take one lens, the 18-135mm will be best; especially since you are driving. There will be many situations where you want the reach. However, you can can compromise with pp - cropping and enlarging.
We will also be taking a long EU trip, but my tradeoff is different. I've been making do with a bridge Canon SX-50 which is quite convenient for traveling. But with only 12 megapixiles, many pictures leave me wanting. I also want to get a new Samsung galaxy Tab S4 before the trip. My wife says to choose one. Boy, women get mean. LOL

KarenKaptures Loc: New Jersey

What he said. I have both and agree. If only taking one, take the 18-135.

AzPicLady Loc: Behind the camera!

As Nancysc suggested, it will depend on what you are shooting. Judging from the countries you say you'll be visiting, I assume you'll be seeing a lot of countryside. You may want some reach there, but the 135 should do it. Distances aren't as great as we're used to. In the cities you'll need closer focusing, as streets are quite narrow. I personally don't like the fisheye look, so I've never had one of those lenses. My standard "walk-around" is a 28-135 that has been redone for crop cameras as the 18-135. It's lightweight, small enough to not poke people in a crowd. Someone mentioned theft. It has been many decades since I was there. When I was there, one could literally leave his camera on a park bench, and it would still be there when he came back for it! Austria was similar. France and Italy, not so much. I like the cotton carrier for safety, as people have to know how to get it off. And the camera is snugly attached to the body, so you "feel" when someone touches it. However, it sometimes takes a few seconds to remove, so you do lose quick shots sometimes.

ChuckMc Loc: Prescott, AZ

The more that I think about your choices, I don't think you can make a bad decision here. As another noted, you'll be taking a lot of pictures where you want the closeup wide angle and as I noted, you'll also be in the countryside where you want the reach, but can make up for the lack with pp. Enjoy your trip, and share with us afterwards!

revhen Loc: By the beautiful Hudson

My experience traveling in Europe and elsewhere with T2i then 70D Canons is that the 18-135 is more than adequate.

shagbat Loc: London

I use Nikon, live in London, and have lived in other EU cities. My most used lens is a 10-20 on dx. With this in mind I suggest you take the 15-85. Only you know what type of shots you will be taking. Have a practice run with both lenses, in a city near you, see if you need the extra reach. Good luck and enjoy your trip!

loosecanon Loc: Central Texas

Ah, the 24mm! Great idea, and I have one. Thanks.

Selene03

I would take the 18-135 and add the 10-18 for very wide angles. Every once in awhile you will want more reach, and one thing about many large cities, especially in Europe is that they are small with very large buildings. The 10-18 is perfect for this. I had this combination on a crop sensor camera in NYC and found myself using the 10-18 a lot more than I thought I would.