In our opinion these are the some most haunted places in the world.
There is no order to the list some are well known and others aren't
Bran Castle Romania
This is the home to what some people consider to be the modern day Dracula, Vlad Die Tepes. He was a prince that ran his thrown with a bloody fist. He used to torture hundreds of people on stakes that has has distributed throughout the ground with in his dungeon and out side the walls of the castle. There was also a story of him inviting 20 homeless people to come in and eat with him at his table and once they were all fed he lite them all on fire on his court yard.

Coronado Hotel California
The story behind this haunting is that there was a young women that was supposed to meet her estranged husband and spend thanks giving together, well he never showed up and a couple days later they found her body at the end of the stairs.

Queen Marie California
This was one of the largest boats to ever sail the water even bigger then the Titanic. Known as the Grey Ghost in WW11 the Queen Marie is supposed to have seen at least 49 deaths on this it and there is supposed to be 12 known ghosts that haunt this ship.

Hot Lake Hotel Oregon
This was at one time a beautiful hotel and then it was turned into a sanitarium and then at last a restaurant when a fire came in a destroyed the place. They say the the doctor that was taking care of the patients at the time of it being a sanitarium used to do experiments on the patients and they still roam the halls and some times you can still hear the piano play.

Alcatraz California
In the late 1930's this became the place for all the hardened criminals of that time. It was used because it the prisoners weren't supposed to be able to break out of it due to it being a deserted place int he middle of the ocean. They shut the doors on this prison in the early 1960s and they say to this day all the people that dies there still walk the halls.

Gettysburg Pennsylvania
This is one of the world bloodiest battle grounds. In the civil war there were hundreds upon hundreds of soldiers that died and lied in piles on the ground int he middle of the battle field as the battle kept on. They say that all the souls for the soldiers still stand their ground on that field.

Auschwitz Poland
This is where Hitler did his dirty deed. this was the most technologically advanced gas chamber of the time. He would take hundreds of Jews and people that were not of the perfect blood line and gas them to death in his chambers. He used to make the other captures take off all the jewelry gold teeth or anything else that was of any value from the bodies before they were put in the gas chamber to suffer the same fate. 
The Weston State Hospital aka Trans Allegheny Lunatic Asylum West Virginia
Due to over crowding in the 1950's the there was a bad case of neglect. They say that there was a lot of people that went missing and that the doctors behind closed doors did experiments on the patients.

Waverly Hills Asylum Kentucky
Waverly was originally built for the growing epidemic of Tuberculosis's, as the numbers of the infected grew the place became it's own world for all the infected and the families that had to be there because of loves ones. There were many of deaths that his place saw and they say that one of the most well known ghosts that walk it's halls is that of a nurse that hung herself.

Poveglia Island Italy
This island became a dumping ground of the bodies of hundreds of people that were infected by the bubonic plague. The body count became so hight that there was bodies that became lining the beaches and would drift from the main part of Venice to this island and litter the shores.