The map below shows T-Mobile's current 700 MHz A, B and C block licenses and leases (pink) and licenses pending FCC approval or sale closing (orange shaded). Officially announced markets where 700 MHz band 12 network has been deployed have a circled 12 placed on them. T-Mobile markets band 12 network as Extended Range LTE. The red circles are TV channel 51 stations protected by the FCC rules. A-block spectrum cannot be used in the red circles until the stations relocate to some other channels. T-Mobile can make deals with the stations to obtain a permission to use A block (concurrent operations agreement). Several deals have been announced and approved by the FCC, see updates below. Stations that are on track to be relocated and stations that gave permission to use A block have a green service contour around them. Stations that applied to relocate have a yellow service contour.
After the 600 MHz auction all channel 51 stations will free up the spectrum within 39 months. During the auction that started on March 29, 2016 the stations will have three choices: exit the business, share a channel with some other station or relocate to some other free channel. In the first two cases the station must free channel 51 within 3 months after the end of the auction. In the third case (they choose relocation) the FCC will pick new channels for all stations and develop an individual relocation schedule for each station. The relocations will take 6-39 months. Read more about the 600 MHz auction and also see an FCC presentation to the broadcasters. RabbitEars published FAQ.
Note that the red service contours are not the exact boundaries of the exclusion zones. For details see this page.
Do you want to know who are the license holders of other areas? Check out Spectrum Omega map (click on the first "700 MHz A block" line in the sidebar).
Questions about the licenses, devices, TV stations, and the 600 MHz auction? Ask /r/tmobile or T4GRU communities.
The map below shows the areas where T-Mobile is unlikely to buy 700 MHz A block spectrum because it's not for sale. Disclaimer: the map is a reasonable guess not a fact. If more information becomes available it will be revised.
Historical map: UHF channel 51 protection zones as of Q2 2014.