UNIT HQ, City of London
Perhaps this should be UNIT HQ (The Star Beast), since UNIT HQ (The Power of the Doctor) was also located in the City Of London. Unless this is a combined page for both, we need some way of differentiating between the two.
Talk about it here.
By late 2023, the branch of UNIT that operated in the United Kingdom had its headquarters (TV: The Star Beast [+]Loading...{"timestamp":"00:49:15","1":"The Star Beast (TV story)"}) located in the City of London, near the Gherkin. (PROSE: The Time Traveller's Almanac [+]Loading...{"chaptname":"Everything Changes","page":"71","chaptnum":"3","1":"The Time Traveller's Almanac (reference book)"}) It had a helipad. (TV: The Star Beast [+]Loading...{"timestamp":"00:49:15","1":"The Star Beast (TV story)"})
History
The previous headquarters was destroyed during the Master's Dalek Plan when Tegan Jovanka and Kate Stewart initiated the structural termination system to implode the building and entomb the Cybermen lead by a cloned Ashad. (TV: The Power of the Doctor [+]Loading...["The Power of the Doctor (TV story)"])
The UNIT HQ was among London's skyline by the time the Meep's attempted Destruction of London was thwarted by the Fourteenth Doctor, Donna Noble, and her daughter Rose. (TV: The Star Beast [+]Loading...{"timestamp":"00:49:15","1":"The Star Beast (TV story)"})
Behind the scenes
This UNIT HQ, going off the on-screen geography seen in The Star Beast [+]Loading...["The Star Beast (TV story)"], appears to be located the financial district of the City of London. However, upon analysing the position further, it makes less sense as it can be seen that the Scalpel and 40 Leadenhall Street are located to the immediate area east, the Leadenhall Building north, the Lloyd's building and Willis Building to the south, and the construction site of 1 Leadenhall Street to the west, thus placing the skyscraper in the middle of Leadenhall Street.
Furthermore, the UNIT HQ seen in The Power of the Doctor [+]Loading...["The Power of the Doctor (TV story)"] is located where the Leadenhall Building is in real life; the road Ace parachutes down towards is Leadenhall Street. The Star Beast (set in late 2023) creates a minor continuity issue by showing that the Leadenhall Building is among London's skyline, despite that tower being non-existent during The Power of the Doctor (set in 2022). The Star Beast also posits that UNIT was able to clear the site of their imploded HQ, deal with the Cyber-Warriors entombed within, and construct their new tower all in the space of a year.
Location information
Though it's possible that a real world location doesn't exist in the same geographic space in the Doctor Who universe, such cases are few and far between. Thus, the map to the right is probably a good indicator of the DWU location of UNIT HQ, City of London.