  We restudy the phase diagram of the 2D-Ising model with competing
interactions $J_1$ on nearest neighbour and $J_2$ on next-nearest neighbour
bonds via Monte-Carlo simulations. We present the finite temperature phase
diagram and introduce computational methods which allow us to calculate
transition temperatures close to the critical point at $J_2 = 0.5 J_1$. Further
on we investigate the character of the different phase boundaries and find that
the transition is weakly first order for moderate $J_2 > 0.5 J_1$.
