Explaining seating areas of the theatre: Stalls, Dress Circle, Upper Circle, Balcony, Boxes
The Stalls is the first (stage) level of a theatre, also called the Orchestra Stalls in America. It is often at street level, although not always.
The next tier is called the Dress Circle or Royal Circle (or just Circle if it is the only additional level in the venue), and which is called the Mezzanine in America.
Some theatres also have additional tiers above the Dress Circle, sometimes called the Upper Circle and the Balcony. Balcony seats are often bench seats.
To see seating plans of each London Theatre, identify the show you want to see and select Find Tickets to see a full plan.
For a guide to Access to West End Theatre see this Accessibility guide produced by the Society of London Theatre.