Yep I have a bunch of these as well,
the overlong descriptions below are partially to aid my own memory in the future. Though my discovering of the World Heritage list came fairly early on in my independent travelling life so I have been a little more savy in researching first.
Batalha, Tomar and Alcobaca in Portugal. Could very easily have visited them but was too polite to get some acquaintances to head out of their way for it. Ended up having a wonderful time in Lisbon instead, so I don't think I did badly. But still it is 3 sites I could have added to my tally, but they are low hanging fruit for my eventual return to Portugal.
Royal exhibition building and Carlton Gardens, I sat in a minibus for 20 minutes directly opposite them at the start of a guided tour on the great ocean road, so easily could of stretched my legs and picked up this most underwhelming WHS. Having some good friends nearby though means I will probably get a future chance with them.
Australian convict sites I had two and a half weeks in Sydney, venturing all over downtown, but some how managed to not visit one of the three sites there, think I saw all of them though without actually visiting them. Oh well I have family there now so I'm sure I will pick them up soon. So a little like
Clyde and his trip to Leeds they may not necessarily be must see sites but the amount of time I wasted in the city without visiting is the root of some frustration.
Saloum Delta, Senegal I spent a slightly frustrating week at a beach resort in The Gambia from which there are easy trips across the border to here,
I even asked for advice on here, but no one was aware of its future prospects. Alas it wasn't inscribed when I visited, but I would have jumped at the opportunity to visit rather than have another day by the pool. Still I did get to meet the enormous and well armed entourage of
His Excellency Sheikh Professor Alhaji Dr. Yahya Abdul-Azziz Jemus Junkung Jammeh Naasiru Deen so at least I got to meet a proper African despot.
Nord-Pas de Calais Mining Basin been through on two occasions and could easily have stopped to see them. Especially irritating as I had a day to kill in Lille, and was some what forced into wasting it, hunting for clothes shops. Should hopefully pick it up in the next few months though along with the Wallonian mining sites! I can't begin to explain how excited Mrs Meltwaterfalls is about the prospect of that holiday :)
Tin mines of Cornwall and Devon technically I have been there twice, though neither time really counts. The second one I even explored a disused shaft of a mine as part of a sea kayaking adventure. Frustratingly the whole trip started a mere 100m from one of the actual sites which I didn't realise until I got back home. It was on my brothers stag party though and there was no way in hell I could convince 15 grown men, mostly in the navy, to visit some industrial heritage sites without endangering my own life and their sanity, so better for all that I did miss that one, my liver still thanks me.
Oh and a pre-emptive one
Namhansanseong Korea, it was on my itinerary but a desire to visit the World Cup museum in Seoul trumped it on my last half day, I rather loved the World Cup stadium though so I don't feel too down. Likewise on the same trip a long hoped for cross border jaunt to
Kaesong was scuppered by a cooling in relations between the north and south.
I'm sure there are more but those are the ones that most spring to mind.
And a quick note on the
Peking man site, I wouldn't beat myself up on it too much, whilst yes it is near Beijing it is well off the beaten path and a tricky one to get to without a decent amount of planning or local assistance.