Great Collection Terrible Space
The original Tate Museum was a cramped museum. It was an old building with a huge collection. When they decided to split its collection between modern art and classic art, they acquired a huge plant on the south side of the Thames, named it the Tate Modern and moved all the modern art.
When the newly-acquired plant was renovated, a decision was made to create a huge, multi-story indoor space for installations and or sculpture that you would generally expect to see out of doors.
This flawed design has left a huge empty space rising from the ground floor to the roof, and cramped galleries all shoved to one side of the building.
After the modern art was moved across the river, the Tate Museum, now known as the Tate British, underwent a renovation.
The newly-renovated Tate British, which is in a modest-sized building on the North side of the Thames, now has more gallery square-footage than the massive building that houses the Tate Modern. This is due to the horrible design of permitting a huge part of the building to remain unusable.
Beware, it is nearly a mortal sin to speak any criticism of the Tate Modern anywhere in London. Londoners are very proud of their modern art museum, but one only need visit any other city's modern art museum to realize what a failure of design the Tate Modern truly is.
The Tate Modern's collection is a must-see. So, if you are a modern-art lover you should go. I recommend seeing the collection; but I will alway commit the mortal sin of saying aloud: The Tate Modern is a terrible space.
The standard travelling modern art shows make an obligatory stop and I recommend booking a ticket in advance for any popular exhibit.