Nice cycle path by Sava and Donava rivers.
There is 3.5 km long cycle path in Athens.
From Koper through Trst to Miramar castle.
From border just follow the brown FVG 2 signs.
It is quite simple: go parallel to the beach for some nice cruising and go perpendicular for some climbing. Or use Diagonal for little bit of both.
Near Agbar Tower you can have fun skating at night on some light installation. You can see this at the end of the video.
When you are in Milan, check this route. You can go around the city, skate in front of the cathedral and all, but this is the part where people from Milan go jogging. And it is quite good for skating too.
Some ‘hill climbing’ in Barcelona.
This is smooth skate along the famous Barcelona beach.
But you have to be very careful, I almost died twice. First time i almost died laughing on all the ridiculous electric scootery things people can rent to try to go around the city, usually on guided tours. One was like electric scooter and home chair conceived an offspring inside Fukushima nuclear reactor. And the other like Pat a Mat trying to build flying carpet out of wheelbarrow and RC car. Later i was almost ran over by a i-dont-know-what-i-m-doing-on-that-thing-but-probably-the-best-i-can-do-is-to-grab-on-those-handels turist. I wasn’t laughing any more.
There are 2 skating parks along the way and some nice spots to do some tricks. You can see them here: http://www.barcelonaskatepark.com/barcelona-skate-spots/
You can use many roads to go from Montjuic (Olympic park on the hill near the sea) to the sea or to the city, even through cementery. The most popular seems to be through the tunnel.
And there is a cable car to go back up.
For longer downhill you can go from Tibidabo. You can use funicular to go up.