(CNN) -- With Adolf Hitler's WWII Bavarian mountain retreat set to undergo a multi-million dollar makeover, travel to the onetime lairs and luxury retreats of tyrants is in the spotlight.
Many monuments built by megalomaniacs are open to the public.
From Tito's nuclear bunker to Stalin's summer house to Mussolini's villa, autocrat hideouts have become tourist attractions.
Does visiting places associated with ruthless dictatorships serve as a useful history lesson? Or is it a disservice to the memories of those who suffered under brutal regimes?
It can be uncomfortable posing for pictures at places where the darkest events of the Third Reich were carried out. Yet the preservation of such sites also serves as an important reminder of historic atrocities.
All of these places are easy enough to get to. Whether you actually want to go is another question ...
Adolf Hitler: Eagle's Nest, Bavaria
This mountain retreat near the town of Berchtesgaden in the Bavarian Alps was originally a place where Hitler could receive visiting dignitaries.
The chalet is reached via a 124-meter elevator drilled into the mountain.
On the same mountain, a backup Nazi command base -- the Berghof -- was destroyed by Allied bombing.
The Eagle's Nest (Kehlsteinhaus, in German), however, is still open as a restaurant and information center -- and a $22.5 million upgrade has recently been announced.
Visitors reach the house by ascending through the mountain in Hitler's brass elevator car
Josef Stalin's Dacha, Sochi, Russia
On the outskirts of the Russian Black Sea resort town of Sochi -- host of the 2014 Winter Olympics -- sits Joe Stalin's summer residence.
Purpose built, complete with palm trees imported from California and sniper emplacements, this was Stalin's favorite escape from Moscow.
It's now a small and somewhat uncomfortable museum, where a waxwork of the mass-murdering Soviet leader can be found sitting at his old desk.
Tours booked via Tours By Locals.
Stalin's summer dacha, Kurortnyj pr. 120, Sochi; +7 8622 970 502
Benito Mussolini: Villa Torlonia, Rome
The neo-classical Villa Torlonia was Benito Mussolini's residence between 1925 and 1943.
The Italian dictator installed a tennis court and hosted movie screenings here.
Now home to a cluster of museums, the Documentation section in the basement shows films from the villa's time under Mussolini.
Elsewhere, it's sculpture, stained glass and city archives with barely a mention of Il Duce's home comforts.
Villa Torlonia Museum, Via Nomentana 70, Rome; Tuesday-Sunday, 9 a.m.-7 p.m.; tickets from €8 ($10.50)
Francisco Franco: Palacio Real del Pardo, Madrid
The Spanish equivalent of Villa Torlonia is the Palacio Real del Pardo, where General Francisco Franco hunkered down for much of his iron-fisted rule.
The hilltop hideaway is now used for keeping visiting heads of state out of harm's way, but when no dignitaries are in town, it can be visited as part of a guided tour.
Anecdotes about Franco's home life are conspicuous by their absence.
El Pardo Royal Palace, Calle Manuel Alonso, Madrid; +34 913 761 500; Monday-Sunday, 10 a.m-8 p.m. from April-September; 10 a.m.-6 p.m. from October-March; tickets €9
Napoleon Bonaparte: Château de Fontainebleau, France
In one of his more egotistical moments, Napoleon decided to spend a fortune revamping the disheveled Château de Fontainebleau.
He wanted the property, about 55 kilometers from central Paris, to top the Palace of Versailles -- which had hated royal associations.
The emperor had his imperial court at Fontainebleau -- more than 1,000 people could stay in the chateau at one time -- and most of the decor and furnishing dates to Napoleon's era.
Château de Fontainebleau Museum, 77300 Fontainebleau; + 33 01 60 71 50 70; open every day except Tuesday, from 9.30 a.m.-5-6 p.m.; €11
Josip Tito: Facility D-0 ARK, Bosnia
Former Yugoslav strongman Josip Tito's bunker in Konjic, Bosnia, was built as a control center for military operations and an atomic shelter for the president and his family.
A labyrinth of underground tunnels, meeting rooms and residential quarters, Facility D-0 ARK was kept secret until the 1990s.
Now, for one summer only, it's been turned into an art project.
Project Biennale has filled the gloomy corridors with dozens of art installations.
D-O ARK Underground; tours on special buses only on Mondays, Wednesdays and Fridays until September 26, 2013, departing from the town of Konjic; +387 61 726 030
King Zog: St. Katharine's Parmoor, England
After being kicked out of Albania in 1939, Albania's autocratic King Zog settled in London's Ritz Hotel before moving to Parmoor House in Buckinghamshire for nearly five years.
The former farmhouse is now St. Katharine's Parmoor -- a religious retreat, usually booked out by groups on weekends, but letting rooms to individuals during the week.
There's little regal grandeur -- just frugal, unfussy rooms and chickens running round the gardens.
St. Katharine's Parmoor, Frieth, Henley-on-Thames; +44 (0)1494 881 037
Adolf Hitler: Wolf's Lair, Poland
Deliberately built miles from civilization in the forests of northeastern Poland, Wolf's Lair was the Nazis' 6.5-square-kilometer eastern front HQ.
Hitler spent nearly three years here in total; it was also the site of the infamous Stauffenberg assassination plot -- which only failed because the meeting room was switched at the last minute.
One of the buildings in the complex is now a hotel (rooms from $38) that offers dubious on-site activities such as a shooting range and tours in military vehicles.
Wolf's Lair, Gierłoż, 11-400 Ketrzyn; +48 89 752 44 29; sightseeing from 8 a.m until dusk, $5 per person