Around Nagoya

We are coming by train from Takayama on April 15 to spend the night in Nagoya. Is there anything interesting on the way to see (old towns, temples etc), which can be easily reached by train as a side trip before arriving in Nagoya? and what is a must-see in Nagoya? not interested in malls etc.

Nagoya's somewhat infamous for perennially coming up tops on "most boring city" surveys ;-) I don't know if there's really any "must-see"s in Nagoya, but Toyota is headquartered nearby, and their factory tour was quite interesting when I did it years ago. Their museum isn't bad either. JR has a train museum too, which I've never been to but looks interesting.

Inuyama Castle is one of only five castles whose main keeps have been designated as national treasures. Inuyama is about half an hour from Nagoya.

http://www.japan-guide.com/e/e3350.html

Legoland Japan will open in April 1st. It is right across from the excellent JR Railway Museum, at Kinjofuta station. From Nagoya Station, take the Aonami Line to Kinjofuto Station.

If you're into sports, the Japan swimming championships will be held in Nagoya on April 13-16.

There's actually quite a lot to see/do in Nagoya. Japan Guide's own entry is a good place to start:

http://www.japan-guide.com/e/e2155.html

My personal favourites are the castle (the newly reconstructed palace in particular), the Tokugawa Art Museum, and of course the fantastic SCMAGLEV and Railway Park. Whether or not these would qualify as "must sees" will depend entirely on your personal interests, but I certainly think they're worth a visit.

From my own trips there (I haven't written much about my latest stay in Nagoya so this isn't even complete):

https://withinstrikingdistance.wordpress.com/tag/nagoya/

Cheers.