Perhaps a bit of an odd question...but a friend of mine is interested in lighthouses.
And I'm wondering if there's perhaps a world heritage lighthouse or a lighthouse which is part of world heritage site? Thx in advance.

There's one in Macao.
And the Tower of Hercules is a Tentative WHS that is up for discussion at the WHC this year.

Off hand (The UNESCO web site is down and I can't check) I can think of
a. Colonia del Sacramento
b. Robben Island (Built 1864)
c. Devon and Dorset coast - Portland Bill lighthouse goes back to 1669 and there are others e.g Anvil point
d. Cape Floral Region - Cape Point lighthouse
e. Galapagos - this site lists 4 locations on these islands
http://www.unc.edu/~rowlett/lighthouse/ecu.htm

I would have thought that there are likely to be a fair number of other non historical operational manned and unmanned lighthouses on inscribed islands or coastal sites. If we are considering a "Connection" it would be necessary to consider which of the above can be viewed as being a significant (rather than an accidental) "part" of the site

I'd consider at least Macao, Colonia del Sacramento and the Portland Bill lighthouse good enough for a connection. Have to check the others too.

Leptis Magna! See for text (scroll)

or even this
http://www.lonelyplanetimages.com/photos/5943-24.htm

Campeche: Ex-Templo de San José (lighthouse atop one of the spires of a church)

This site has more than one is ever likely to need to know about lighthouses -and photos of most of them.

http://www.unc.edu/~rowlett/lighthouse/index.htm

I will leave someone more dedicated than I to trawl through it (EnsignYoshi's friend??)
I have picked out
Curonian spit - Nida/Nidda
Brazil - Atlantic Islands

And how could I have forgotten this one: Schokland (replica of one from 1915 at the old harbour of Emmeloord, with next to it the original house of the lighthouse keeper)

My old favourite Skellig Michael has one, it used to have two.
The current access ramp and slip way were built for the maintinance of the lighthouse.

That's already more than I was hoping for :)
Thx everyone. he's going to love reading this