Start service?

I am trying to write this sentence:

"The pavilion was built in celebration of the start of the service of the entire North-South railway."

There are just too many ofs and thes. I don't know how I can express this better.
And, the "entire" means part of the railway had already started service. The pavilion was built when every part of it had all started service...
Can anybody help me?

Maybe, "The pavilion was built to celebrate the start of service along the entire North-South railway."

I would put it this way:
The pavillion was built for the inauguration of the entire North-South railway.