TV begs the question, 'When are we now?'

The following dramas about the topic of time travel are perhaps the most acclaimed - of all time, that is.

Doctor Who (1963-89; 2005-present)

This BBC sci-fi drama depicts the adventures of a time-traveling alien named "Doctor Who". The humanoid explores the universe in a blue time machine called TARDIS, which resembles a 1950s British police booth.

He battles evil with a series of companions as he bounces around in time and space.

Dr Who remains the longest-running sci-fi series in the world. The 2005 version picks up where the previous 26-year run left off. Eleven actors have played the main role.

Life on Mars (2006-2007)

This BBC series fuses the police procedural and time travel genres in telling the tale of a cop, whose present-day auto accident sends him back to 30 years previous.

While stuck in the past, he is on the trail of several killers - and the reasons he was sent back and how he can return to his own time become evident.

Lost (2004-2010)

Awash with flashbacks and fast-forwards, time travel dominates ABC's mind-bending labyrinthine drama.

The show revolves around plane crash survivors stranded on a tropical island occupied by mysterious entities.

It uses the time-warp gimmick to provide viewers pieces of the puzzle.

A Step into the Past (2001)

This Hong Kong period drama, based on a popular martial arts novel, is a smash hit that centers on a special agent who becomes the subject of a time travel experiment.

He returns to the Warring States Period (475-221 BC) and helps Yin Zheng - aka Qin Shihuang - become China's first emperor.

Love through Different Times (2002)

A thief who steals a Ming Dynasty (1368-1644) magic pillow and the policewoman who tries to arrest her are both sent back to the Ming era and form a love triangle with the dynasty's founder, Zhu Yuanzhang.

The series fuses humor and action with clever plot twists.

The Myth (2010)

A TV adaptation of Jackie Chan's eponymous kungfu fantasy centers on a freelance photographer (played by Hu Ge), who is transported to the Qin Dynasty (BC 221-206) after he opens a treasure chest.

He becomes a valiant general entangled in dynastic power struggles, who falls in love with a princess.